______ at the letter, which was________ to my classmates

I believe that he _____ us as soon as he comes back toChina.

The volunteers try to convince people _____the fact that some species are in danger of _____.

Some theories believe ____ quality input ensures quality output in English learning.

What’s the matter with Della? — Well, her parents wouldn’t allow her to go to the party, but she still ________.