Will, would, and used to

We can use will (for the present) and would (for the past) to talk about characteristic behavior or habits, or about things that are or were always true:

John will come to work and turn on the air conditioner every day. 

During the pandemic, people would do all kinds of jobs that we don't do now.

A baby will recognize its mother's voice soon after it is born.

Early passenger planes wouldn't hold more than 30 passengers.

We don't use would in this way to talk about a particular occasion in the past. 

Compare:

Each time I had time I would go out with my family. and

Last night I had time so I went out with my family. {not ...I would go out with my family...)

In the speech, we can stress will or would to criticize people's characteristic behavior or habits:

She will leave all the lights on in the house when she goes out.

I was happy when Sam left. He would talk about people behind their backs.

When we use stressed would in this way, we can also use it to talk about a particular occasion in

the past. We suggest that what happened was predictable because it was typical of a person's

behavior:

'Jackie says she can't help because she's got a lot of work on.' 'Well, she would say that - she

always uses that excuse.'

If we want to talk about things that happened repeatedly in the past, but don't happen now, we

can use would or used to + infinitive. Used to is more common in informal English:

We would / used to eat less when we didn’t have much money. 

Ted would / used to visit his parents every other weekend.

We use used to but not would when we talk about past states that have changed:

The factory used to be in the city center.

I used to smoke heavily when I was at university.

When we use would we need to mention a specific time or set of occasions. 

Compare:

We used to play in the garden, {not We would play...)

Whenever we went to my Uncle John's house, we would / used to play in the garden.

We don't use either used to or would when we say exactly how many times something

happened, how long something took, or that something happened at a particular time:

We visited Japan four times during the 1990s.

She went on holiday to the Bahamas last week.

Study how we normally make questions and negatives with used to in spoken English:

Did your children use to eat vegetables when they were young?

I didn't use to play computer games when I was young.