will be able to

[Unregistered]

Hi, my name is Cosmos. I teach English at high school.
I would really appreciate any advice from you.

My question:

(a) Unfortunately, I cannot attend Friday's get-together.
(b) Unfortunately, I am unable to attend Friday's get-together.
(c) Unfortunately, I won't be able to attend Friday's get-together.

Grammar books say that the future tense of "can" is "will be able to".
If this rule is strictly applied, then only (c) would be grammatically correct, since the act of "attend" occurs in the future. But in fact it seems that (a) and (b) are often used.

Can "can" and "is/am/are able to" be used instead of "will be able to", regardless of what grammar books generally say?

Also, please tell me if there is any difference in formality of speech among (a) (b) and (c).

[riverkid]

Hi, my name is Cosmos. I teach English at high school.
I would really appreciate any advice from you.

My question:

(a) Unfortunately, I cannot attend Friday's get-together.
(b) Unfortunately, I am unable to attend Friday's get-together.
(c) Unfortunately, I won't be able to attend Friday's get-together.

Grammar books say that the future tense of "can" is "will be able to".
If this rule is strictly applied, then only (c) would be grammatically correct, since the act of "attend" occurs in the future. But in fact it seems that (a) and (b) are often used.

Can "can" and "is/am/are able to" be used instead of "will be able to", regardless of what grammar books generally say?

Also, please tell me if there is any difference in formality of speech among (a) (b) and (c).

The grammar books have gotten more than this wrong, Cosmos. English doesn't have a future tense but traditional grammar got so hung up on 'will' as the future tense of English that they missed all the other ways we have to express the future.

So, in a nutshell, yes, you can use the other ones you've mentioned/you mentioned. As to formality, they all sound fairly formal.

[sakura-saku]

Thank you, riverkid.
I appreciate your comment very much.

So there ARE cases where you can use "can" and "is/am/are able to" to indeicate the future event.

May I ask you one last question?
Is there any case in which you can use "will be able to", but not "can"?
If the answer is Yes, a sample sentence would be greatly appreciated.


P.S. I have now registered and my new name is sakura-saku.

[riverkid]

Thank you, riverkid.
I appreciate your comment very much.

So there ARE cases where you can use "can" and "is/am/are able to" to indeicate the future event.

May I ask you one last question?
Is there any case in which you can use "will be able to", but not "can"?
If the answer is Yes, a sample sentence would be greatly appreciated.


P.S. I have now registered and my new name is sakura-saku.

Welcome SS. How's the weather in Tokyo? It's minus 22 here.

Off the top of my head, I'd say no to your query. Let me give this some more thought and I'll reply tomorrow. In the meanwhile somebody else may offer their thoughts.

I'm off to bed.

Oyasumi nasai.

[sakura-saku]

Hi, riverkid.
Thank you for your reply.
It's prettey warm here in Tokyo--15 degrees Celsius.

I'm looking forward to hearing from you tomorrow.
Oyasumi-nasai.