Use of shall be able / Will be able

Affirmative sentences 

Tense	Modal	Form
Simple Present	I can play football.	I am able to play football.  I'm able to play football.
		I am allowed to play football.  I'm allowed to play football.
Simple Past	I could play football.	I was able to play football.
		I was allowed to play football.
will-future	Do not use can in the will-future.	I will be able to play football.  I'll be able to play football.
		I will be allowed to play football.  I'll be allowed to play football.

Other possible tenses: 

e.g. Present Perfect: I have been able to play football.

 

Negations 

Tense	Modal	Form
Simple Present	I cannot play football.  I can't play football.	I am not able to play football.  I'm not able to play football.
		I am not allowed to play football.  I'm not allowed to play football.
Simple Past	I could not play football.  I couldn't play football.	I was not able to play football.  I wasn't able to play football.
		I was not allowed to play football.  I wasn't allowed to play football.
will-future	Do not use cannot in the will-future.	I will not be able to play football.  I won't be able to play football.
		I will not be allowed to play football.  I won't be allowed to play football.

Questions 

Tense	Modal	Form
Simple Present	Can he play football?	Is he able to play football?
		Is he allowed to play football?
Simple Past	Could he play football?	Was he able to play football?
		Was he allowed to play football?
will-future	Do not use can in the will-future.	Will he be able to play football?
		Will he be allowed to play football?