ANSWERS TO THE PUZZLE:

1 - The drinks are on the house.
2 - The blouse and the skirt go together.
3 - It won't do any good.
4 - I hinted at it.
5 - Forgive me for saying so.
6 - It's him all right.
7 - He filled in for a sick colleague.
8 - He substituted for the regular teacher.
9 - I glanced over it.
10 - Why, of course!
11 - That's not quite what I meant.