be able to

[John]

Are these all OK and natural?

1-1. I'm sure you can swim well soon.
1-2. I'm sure you will be able to swim well soon.
1-3. I'm sure you are able to swim well soon.

2-1. Wait a while. I can be back soon.
2-2. Wait a while. I'll be able to be back soon.
2-3. Wait a while. I'm able to be back soon.

Thanks.

[Rusty]

Are these all OK and natural?

1-1. I'm sure you can swim well soon.
1-2. I'm sure you will be able to swim well soon.
1-3. I'm sure you are able to swim well soon.

2-1. Wait a while. I can be back soon.
2-2. Wait a while. I'll be able to be back soon.
2-3. Wait a while. I'm able to be back soon.

Thanks.



1-1. I'm sure you can swim well soon. (To express future ability, can shifts to be able to. See:
http://www.englishpage.com/modals/can.html
1-2. I'm sure you will be able to swim well soon. (OK).
1-3. I'm sure you are able to swim well soon. (Incorrect).


2-1. Wait a while. I can be back soon. (Because soon is in the near future the use of can seems natural. Example: I can be back in a minute. This sentence is different from 1-1. Learning to swim soon is not something that will happen in a few minutes).
2-2. Wait a while. I'll be able to be back soon. (This is grammatically correct, but 2-1 is more common when using soon).
2-3. Wait a while. I'm able to be back soon. (No).