1. To be able to

2. Subject + ‘to be’ able to + infinitive
‘be able to’ is used to say that you can do something, it is within your possibilities
We always write:
Subject + ‘to be’ able to + infinitive
I am able to explain you how it works.
Julie is able to type 180 letters per minute.
Do you think you’re able to lift that weight?
Is your dad able to drive us to football practice?

3. Subject + ‘to be’ not able to + infinitive
To be able to
If we ad ‘not’, we can also use ‘be able to’ to say that you can’t do something, that it isn’t within your possibilities
We always write:
Subject + ‘to be’ not able to + infinitive
I’m not able to explain you how it works.
Julie isn’t able to type 180 letters per minute.
Do you think you aren’t able to lift that weight?
Isn’t your dad able to drive us to football practice?