Ask if you can do that.
Please do that.
You can't go there.
It isn't necessary to do that.
You are able to do that.
You weren't able to do that.
I can't move my arm.
I think it's that.
You needen't do that.
You can do that.
May I do that?
It might be that.
You couldn't do that.
Would you do that?
It's forbidden.
I think it's broken.
