—This teaching method seems good.—True. It can be __________ in a few selected schools to see how it works in practice.

—I heard that Mary had ________ with her friend. —Really? No wonder they don’t speak to each other any longer.

Rather than ______ home, he always prefers _______ on the street when his parents  quarrel.

David was ____ in the second half of the football match after a serious knee injury.

Don’t you realize the ________these chemicals are doing to our environment?