温度、湿度、火灾、地震等属于下列哪种因素（）。
A. 人为因素
B. 环境和灾害因素
C. 系统自身因素
D. 以上都不是
They usually wear a collar and tie ______ …
A. as they work
B. to work
C. going to work
D. in order to work
Alf was ______ anything to his wife.
A. so embarrassed he said
B. very embarrassed and said
C. very embarrassed, so he said
D. so embarrassed he did not say
He told her that he worked for the Corporation ______ …
A. simply
B. in a simple way
C. and no more
D. only
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