—I called you at 5:00 yesterday afternoon, but no one answered.
—Sorry. I _______ football with my friends at that time.
A. play B. played C. will play D. was playing
We need clear air and water, so we _____ protect the environment.
A. can B. may C. must D. might
He spent a lot of time on English. ______, he got the most points in the English test.
A. In fact B. Otherwise C. As a result D. However
______there is no buying, there will be no killing.
A. If B. While C. Because D. Since
Wolves have good team work. They usually work _____a team when they hunt.
A. for B. as C. of D. in
The environment here becomes better and better. ______ birds are coming back.
A. Thousands of B. Thousand of
C. Thousands D. Thousand
