These books are _____. _____ are in _____ bags.

On ______ sides of the streets are a lot of colorful flowers.

You’ve dropped __________ “s” in the word “across”.－Oh, you are right, __________ letter “s” should be doubled like this “cross”.

Are ________ her parents?

Why do you ____ very happy this afternoon?—Because we are going to spend the evening at Lily’s house.