W: In this city there are many types of transportation available. Which do you use, FredM: The buses are so crowded that I usually take the tram. Why does Fred prefer to use the tram（）
A. They are faster.
B. It is the only thing available.
C. Buses are not safe.
D. Buses are too crowded.
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They talked in a low voice（）heard by the man standing against the wall.
A. so as to not be
B. as to be not
C. so not as to be
D. so as not to be
I could easily have imagined her（）him as a man of fine quality.
A. thinking
B. regarding
C. taking
D. admitting
All the letters（）,John took them to the post office.
A. had been writing
B. having been written
C. wrote
D. had written
The ability to use a language can be（）only by the act of using the language.
A. acquitted
B. acquired
C. inquired
D. required
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