1. Most birds find it safe to sleep in the trees, but _____ they have eggs or young chicks, they don’t use a nest.
A. why B. how C.unless D. where
1. ---What were you doing when Tom came to see you?
---I had just put on my overcoat and_____ to visit my friends.
A. left B. was left C. was leaving D. had left
1. As ______along the river bank, she was singing a pop song.
A. walking B. walked C. to walk D. walk
1. _____ is known to everybody, Taiwan is part of China. We must unify it.
A. It B. As C. That D. What
1. ---I rang you yesterday afternoon. A man answered, but I didn’t recognize the voice.
--- Oh, it ____ my uncle. He was in my room then.
A. must have been B. should have been C. must be D. should be
1. Mrs.Black took the police back to ____ place ____ she witnessed the robbery. A. the same, that B. the same, as
C. the same, where D. as the same, as
