This document discusses the use of "be able to" to express ability in English. It notes that "be able to" can be used instead of "can" and "could" and provides examples of its structure and use in different tenses. Key points include: - "Be able to" has the structure of subject + be + able + infinitive - It can be used in all tenses like the present ("I am able to drive") and past ("I was able to drive") - It also has an infinitive form ("I would like to be able to speak Chinese") - "Be able to" is useful when wanting to express ability in other tenses or using the infinitive

1. BE ABLE TO
We sometimes use it instead of can and could, to talk about ability. Look this chart:
The structure of be able to is:
subject + be + able + infinitive
subject be
main verb
able
adjective
infinitive
+ I am able to drive.
- She is not able to drive.
isn't
? Are you able to drive?
Notice that be able to is possible in all tenses, for example:
 I was able to drive...
 I will be able to drive...
 I have been able to drive...
Notice too that be able to has an infinitive form: I would like to be able to speak Chinese.
If we say "I am able to swim", it is like saying "I can swim". We sometimes use "be
able to" instead of "can" or "could" for ability. "Be able to" is possible in all
tenses - but "can" is possible only in the present and "could" is possible only in the
past for ability. In addition, "can" and "could" have no infinitive form. So we use "be
able to" when we want to use other tenses or the infinitive. Look at these examples:
 I have been able to swim since I was five. (present perfect)
 You will be able to speak perfect English very soon. (future simple)
 I would like to be able to fly an airplane. (infinitive)

2. BE ABLE TO
PRACTICE
(COPY THIS PAGE IN A NEW ONE AND COMPLETE THE EXERCISES, FILE IN YOUR DESK AND THEN
SEND IT TO ME BY FACEBOOK. DON’T SHARE YOUR ANSWERS WITH ANYBODY)
I COMPLETE THE FOLLOWING SENTENCES WITH CAN/COULD/BE ABLE TO… AND
WRITE THE NUMBER IN THE CIRCLES.
1. Carlos ……………..…. to play the guitar.
2. Super Boy ……………….. play very high.
3. When Jose was 8, he …….…………. ride the bicycle.
4. ……………… you sweep the floor?
5. My brother will ……………… to sing in the concert tomorrow.
6. Pete ……………… to play with cars, isn’t he?
7. I …………………. to answer all the exercise.
8. My friends have …………………..to win all the championships since 2012.
II CHOOSE ONE ALTERNATIVE TO COMPLETE THE SENTECE.
1. I ______________ remember his name. (am not able to / can't)
2. You'll be able to solve this, ______________? ( won't you / will you)
3. Diana ______________ the piano. ( can play / can to play)
4. She ______________ come on holiday next month if her parents give her permission.
(could / will be able to)