It was in a mountain village, the professor said, _____ two of his assistants were working as volunteers.

A. where               B. which               C. whose               D. that

The boss got very annoyed and ________（撕）the letter to pieces.

How can you keep _________（沉默）on so important a problem?

On my way to the concert, the street was  c       with so many people that my car could only move very slowly.

There will be a _________（現(xiàn)場的）broadcast stand-up comedy on TV next week would you like to watch it?

The girl once worked as a volunteer in a mountain village from which she has  b       a lot.

The manager ___________（表揚）him for his completing the task perfectly the other day.

We should take  m        to prevent the lake from being polluted.

On his ________（到達(dá)），he got down to doing research into his subject.