3 Short conversation[音频]
A. Charlie Chaplin's films are too serious.
B. Charlie Chaplin's films are very creative.
Charlie Chaplin's films can't be understood easily.
D. Charlie Chaplin's films can't be compared with other films.
4 Short conversation[音频]
A. The car.
B. The phone.
C. The computer.
D. The light bulb.
5 Short conversation[音频]
A. Bob remembered all his lines.
Bob performed very naturally.
C. Bob should be proud of himself.
D. Bob should have performed better.
当荷载随时间作周期性变化时，称为交变荷载。（ ）
A. 对
B. 错
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