Used to, would and be used to

It's important not to get confused with these three expressions:
Used to + infinitive
Used to is a modal verb that shows a habit in the past. It shares some characteristics with other modal verbs:

• It does not have an infinitive form and, instead of being preceded by to, it is followed by it.
• It has only one form for all the persons: I used to smoke / He used to smoke.
• It cannot be used in all tenses: *I use to smoke (not possible). Used to is always in the past. In order to express a habit in the present, the present simple tense is used together with adverbs of frequency (usually or generally): He usually smokes twenty cigarettes a day.
• It is always followed by another verb: We used to study hard when we were at university.
• It doesn't need an auxiliary verb for questions and negative sentences. Used he to smoke? He used not to smoke, but now he does. However, that form is considered very formal and it is more common to use the auxiliary did in these cases: Did he use to smoke? He didn't use to smoke, but now he does. Please, notice that after the auxiliary verb did, it drops the final d.

He used to smoke
Image: Homer's first smoke, by Kevron

The verb used to followed by a verb in the infinitive can express:

• A habit in the past.  I used to smoke, but now I don't smoke at all.
• A repeated past action. In this case, would can also be used: When I was a child, my mum used to / would tell me fairy tales every night before going to bed.
• A state which no longer exists: I used to have a motorbike, but I sold it.

Be used to + gerund / noun

It means that something is familiar and you are accustomed to it. It can be used in all tenses, as the main verb is to be and used is an adjective not a verb. Please, notice that this structure is followed by a noun: I am used to the traffic because I live in a big city. or a gerund (-ing): He has lived in Britain for a long time, so he is used to driving on the left.

Get / become used to + gerund / noun
It expresses the process of something becoming familiar to us. It can also be used in all tenses for the same reason. You will get used to cooking in your microwave soon. I have become used to doing all my work on the computer.

Driving on the left
Image

In these three structures, used to is pronounced [juːst to] and shouldn't be confused with the verb use [juːz], meaning "employ", "utilize", or its participle used [juːzd].
These exercises will help you check what you have learnt:

Need more exercises?:
Complete the sentences.
Mix and match
Used to or would

Now you can watch this video of a song titled "Somebody that I used to know" by Gotye.