MEANING

I won't do it vs I don't want to do it

I'm learning English and i would like to know if there is a difference in this sentence between won't and don't want to :

She won't explain what happened.
She doesn't want to explain what happened.

Thank you for your help !

*** I won't do it vs I don't want to do it ***

The term "won't" actually means "will not"

She won't explain what happened. = She will not explain what happened. (Like she's 100 % sure)

The meaning is similar but it's not the same. For instance:
She won't go to school tomorrow, because she is sick. -> 100 %
She doesn't want to go to school tomorrow, because she hates her teachers, but her mother will make her go anyway.

"Won't" - when talking about volition - is actually stronger than "doesn't want to" - it's closer to "refuses to".

It's possible, for example, to say "she doesn't want to do it, but she will".

It's not possible to say "she won't do it, but she will".

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“downtime” vs. “time off” vs. “free time” vs. “spare time.

Please, compare:

Everyone needs downtime to unwind.
Everyone needs time off to unwind.
Everyone needs free time to unwind.
Everyone needs spare time to unwind.

"Free time" and "spare time" are mostly synonymous and imply that your existing or habitual schedule has leftover time that you can allocate (1) as you see fit. The dictionary notes about hobbies or "free from responsibilities" is referring to this. (1) distribute, share, assign.

Even though I work 50 hours a week, I still find free time to spend with my family.
Even though I work 50 hours a week, I still find spare time on the weekends.

"Downtime" and "time off" both imply some form of disruption in your existing or habitual schedule. The key difference between these and "free time" is that "downtime" is a change and "free time" is part of the normal schedule.

I have been working in this industry for 20 years without a vacation. I need some time off. (a time period when you are not required to work; "he requested time off to attend his grandmother's funeral") Syn: time out - a pause from doing something (as work); "we took a 10-minute break"; "he took time out to recuperate"
It has been go, go, go all year. I'm looking forward to some downtime this fall.(tiempo muerto vs uptime)

The difference between "downtime" and "time off" is mostly in connotation but for the scope of this question they are synonymous. If you are curious about the nuances between those two in particular, feel free to ask a separate question.

To explicitly address your examples:

Everyone needs downtime to unwind. (rest, relax, cool off, cool down).
Everyone needs time off to unwind.

@ cool it, [no object] Slang. calm down:Cool it before you say something you'll be sorry for.

These mean, "Everyone needs to take a break from the normal schedule to unwind."

Everyone needs free time to unwind.
Everyone needs spare time to unwind.

These mean, "Everyone should allocate time to unwind in their schedule."

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What is the difference between someone and somebody?

someone is used for a more special person and somebody for a person in general.

There's someone at the door.
I'd like to be somebody.

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“stay home” vs. “stay at home”

Consider the following:

I'll probably stay at home.
I'll probably stay home.

Is the second sentence still grammatically correct? Is there any difference at all?

Both are correct. There are instances where they mean the same thing and some instances where they don't.

If you were telling someone that you didn't intend to go out tonight, you could use either.

"Do you want to go with us to a restaurant tonight?"
"No, I think I'll stay home."
"No, I think I'll stay at home."

However, if someone were asking where you were staying, where the answer might be "a hotel" or "a friend's house", you would definitely say "at home".

"Are you going to get a hotel room for the conference?"
"No, I'm going to stay at home."
~~"No, I'm going to stay home."~~

(Note that if you did say the struck-through version, that would tend to imply that you weren't going to go to the conference at all.)

However, that "home" is uncommon in that it also functions as an adverb. You can never leave the preposition out with other similar nouns. For example, this is clearly wrong:

"I'll probably stay work."

The difference between WILL, BE GOING TO and THE PRESENT CONTINUOUS for future events.

WILL and BE GOING TO for future intentions

Will (future simple) is used to express future intentions that are decided at the time of speaking (spontaneous offers, promises and decisions):

Come on, I'll help you with those bags. (seeing that someone is struggling with their shopping bags)

Be going to is used to express future intentions that have already been decided before the time of speaking:

I can't make it on Saturday. I'm going to help my parents around the house. (referring to a decision that the speaker has made in the past)

WILL and BE GOING TO for predictions

Will (future simple) is used to make predictions that are based on personal judgement, opinion or intuition:

I'm sure you'll have a lovely time in Italy. (opinion)

Be going to is used to make predictions that are based on present evidence. The predicted event is either very near (and can be seen) or seems sure to happen:

My sister's going to have a baby. (we can see that she is pregnant)

BE GOING TO and present continuous for future plans

Be going to refers to future intentions that have been decided but have not been fully planned:

We're going to get married. (referring to a past decision)

The present continuous tense refers to fixed future events and emphasises that plans or arrangements have already been made:

We are getting married next month. (the wedding has already been arranged)

It will / is going to rain
Hi guys.

Could you tell me if there is any difference between "It will rain" and "It's going to rain" in terms of degree of formality, probability, etc.?

I think they are interchangeable. "It will rain" might sound a little bit more certain, but there are no big differences.

"It's going to rain" typically implies that it will happen sooner. Ex: "It's going to rain this afternoon."
"It will rain" is used more often for the farther future, such as "It will rain the whole summer."
However, "It's going to rain" is used in common speech much more often, even for the distant future, as it's less formal. If someone was to use "It will rain" in speech, it would pretty much always be in contracted form "It'll rain this saturday."

a) I think it is going to rain this afternoon.
b) I think it will rain this afternoon.

I think your assumptions are wrong, TL.

In both cases the speaker is expressing a personal opinion (after all, he says "I think"), and I would not distinguish between "will" and "is going to" on the basis that in one case the opinion is influenced by evidence, while on the other it's just a random result of crystal-ball-gazing. I'd say in both cases both versions are interchangeable.

They would still be interchangeable without "I think". Think about it. Without "I think", it would seem the speaker is stating more than an opinion, a belief verging on certainty. He is sure that it will rain. He is sure that it is going to rain. I again see it as irrelevant how he came to be certain, and if he's just guessing, he wouldn't be certain.

Thanks once again. Crystal clear!

BE + TO-infinitive

Be + to-infinitive is used to express:

official arrangements:

The Prime Minister is to visit India next month.

official orders:

At the end of the course, all students are to take a written exam.

things that should be done:

What am I to do?

a possible aim when saying what should be done to reach it:

If you are to work here for more than three months, you must have a residence permit.

prohibition (only in the negative):

You are not to do that again.

Be + to-infinitive can also be used in the past:

Mr Jones was to speak at the meeting. (it was arranged and he did)

But was/were + to + perfect infinitive means that the arranged event did not actually happen:

Mr Jones was to have spoken at the meeting, but he had to cancel because of his illness.

HAVE TO BE vs ARE TO BE

Looking at difference in meaning between have to be and are to be:

have to be expresses a prerequisite for the show. If the instruments are not tuned, the show can't start. It is therefore closely related to "the instruments must be tuned" (but not the same)
are to be expresses a lower sense of necessity that the instruments are tuned, and rather indicates that doing so is general procedure. It has less emphasis on the "must", and instead it seems to convey that "this is always the case so the instruments will also be tuned this time". Like Grizzly suggested, it is expressing the expectation that the instruments are tuned.

Must vs. Have to

Sometimes we can use must or have to to mean the same thing.
* I need to be at the airport in one hour, so I must / have to go.

Generally, we use must for expressing personal feelings, and have to for expressing facts.
* That new restaurant is great! You must go there!
* You have to turn off your mobile phone in a museum.

We use must for the present or future, but not the past. We can use have to for all tenses (i.e., change have to to had to).

For negative statements and questions, we generally use do / does / did with have to.
* You don't have to participate in the phone conference.
* Why did you have to tell the boss what I said?

Must not / mustn't and don't have to have different meanings. Must not / mustn't means it is forbidden. Don't have to means it is not necessary.
* You mustn't do personal work on the company's computers.
* You don't have to attend the meeting if you don't want to.

Past and future tense of 'must'

'Must' is effectively the present tense form of a modal verb. Because of the nature of one of its meanings (roughly: be obliged to), what one is obliged to do usually happens after the obligation is imposed:
* He must (present obligation) go (in the future) to the doctor.

Like all modals, 'must' has no future form; we have to use an alternative way of expressing the idea:
* He will have to (future obligation) visit the doctor. 'Must' has no past tense form; once again, we have to use an alternative way of expressing the idea:
* He had to visit the doctor.Note:
* He must not go = He is obliged not to go.
He needn't go/ He doesn't have to go = There is no obligation for him to go.
'Must' can also convey the idea of 'it is a logical assumption that':
* He hasn't been to work all week. He must be ill.

If we assume, in the present, something about a past state, we express it thus:
* He must have gone to the doctor. = It now seems logically certain that he went to the doctor.

Assume vs. presume

Assume and presume both mean to take something for granted as true (among their many other definitions). The difference is in the degree of certainty. A presumption is usually more authoritative than an assumption. To presume is to make an informed guess based on reasonable evidence, while to assume is to make a guess based on little or no evidence.
* (suppose): Many people assume that a tie indicates a person of authority.

* (take for granted): This course assumes a basic knowledge of Spanish.

Seem vs. look

Mostly they're equivalent but it's possible to think of specific examples where one would fit better than the other:
* "She seems very kind" is better than "She looks very kind".

(Beware that when you say "She looks attractive", "look" here is used in another sense and it is NOT equivalent to "seem".)
"To seem" is always to resemble or to appear or to be probable: and
* She seems tired, but I'm not sure. * I seem to have lost my wallet. (aspect, appear): parece (que)
* It seems to be true that they are on vacation. (parece)

"To look" primarily refers to sight:
* The children's toy had the look of a real pone. (la apariencia)
* He looked tired when he arrived last night. (appear)
* He looks sick. (seem to be).

"To look" takes on the same meaning as "to seem" (resemble) when it is used with 'like'.
* "You look like Charlie Chaplin." (You resemble Charlie Chaplin.)
* "It looks like it's going to rain." (It appears that it is going to rain.)

Or, if it's a purely visual appearance, you can leave off the 'like':
"You look terrible." (Your visual appearance is terrible.)

Diferencias entre "seem", "look", "appear"

- She looks tired. Parece cansada.
- She seems tired. Parece cansada.
- She appears to be tired. Parece estar cansada.

Nota: Aquí los tres verbos coinciden, pero con "appears" uso la expresión: "appears to be" parece estar. Sin el "to be" el significado del verbo "appear" cambia, significa "aparecer", por eso, utilizo "appears to be" .

"Seem" y "appear" no se pueden utilizar de forma alternativa con "look" en expresiones que no indican "apariencia física".
- She seems (to be) annoyed with / angry at me (when hearing so on the pone)
- It seems to be working. Parece que funciona (una máquina, por ejemplo). También podríamos decir: "It appears to be working." Pero no decimos: It ~~looks~~ to be working.

Compara:- It seems to be broken. Parece que está roto. Nota: Me fijo en el resultado.
- It looks good. (un lugar) Tiene buen aspecto. Nota: Me fijo en la apariencia externa.
- It seems good. (una cosa o actividad) Parece bueno/a. Nota: Describo una cosa o una actividad.
- He seems to be understanding. Parece que él está entendiendo. Nota: También es posible: He appears to be understanding. No digo: He ~~looks~~ to be understanding.¿Por qué? No es la apariencia física lo que me preocupa, sino la parte interior de la persona.

angry with someone vs angry at something / ing
angry with/at so.
* I get angry at myself for staying in relationships way too long.

to be angry at sth (angry about" or "angry that ...)
* The clubs have been angry at having to carry some of the costs of the game's intensified security on match days

OTHER USES OF WILL

We use 'will' for habit.
* Boys will be boys:
said to emphasize that people should not be surprised when boys or men act in a rough or noisy way because this is part of the male character
* A cat will always find a warm place to sleep.
* My car won't go any faster than this.

We can use 'will' to describe present habits and behaviour whether it is good or bad.
* She'll tell you all about her life even if you're not interested.
* He will always wake up early.

We use 'will' for deduction.
* I expect he'll want us to get on with it.
* The phone's ringing. That will be Mark.

EMPHASIS

"if this happens" = "Sí esto sucede..."
"if that does happen" = "Y sí eso si sucede..."

COULD VS WAS ABLE

Could is used to talk about a general ability in the past.
Was able to is used to talk about an ability on a specific occasion in the past.

couldWhen John was 16, he could already drive.
At the age of seven, Lisa could already speak three languages.
Matt was very smart, he could beat anybody in his class.
was able toJohn got lost but he was able to get back home by taxi.
When Lisa was in France, she was able to talk with the locals in French.
In the final test, Matt was able to get the best score.

ANNOYANCE

To express annoyance we tend to use the 'present continuous + always, keeps + ing' or 'will keep + ing' in the same way.
* My sister is always telling me what to do.
* He keeps texting me.
* They will keep reminding me to go and visit them.

PAST HABITS

For past habits we can use 'would'.
*My father would take me fishing every Saturday.

It is important to remember that 'will/would' are used to describe habits not states:
He would get angry very quickly. NOT He would be angry very quickly.
And the 'present continuous + always, keep +ing and would keep + ing' are used the same way.
'Keep on' is used to emphasise that the action is repeated frequently.
* I'm sorry but I keep forgetting your name.

PEOPLE'S HABITS. TYPICAL STATES.

'Tend to' is used to describe typical states.
* She tends to be rather shy in new company.

Habits Expressed by "Will" and "Would"

General statements

It is chiefly used in general statements. For example:

An Englishman will usually show you the way in the street. (It is normal for an Englishman to act in this way.)
She will always greet you.

Past routines

This is not a very important use of "will", but the past form, "would", has a much wider use and can replace "used to" when we are describing a past routine:
Take this sentence for an example:

On Sundays he used to (or would) get up early and go fishing. He used to/would spend the whole day by the river and in the evening used to/would come home with marvellous stories of the fish he had nearly caught.

Note, however, that when used to expresses a discontinued habit, it cannot be replaced by "would". Both "will" and "would" can be contracted when used as above.

Obstinate insistence, usually habitual: Boys will be boys

Use "will" to express obstinate insistence, usually habitual:

If you will keep your watch half an hour slow, it is hardly surprising that you are late for your appointments!

"Would" is used in the past:

We all tried to stop him smoking in bed but he would do it.

Will and would are not contracted here and are strongly stressed.

Would can express a characteristic action, usually one which annoys the speaker:

Bill objects/objected = He would object. (He always objects.)

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