柴油机运转时,( )等对零件的疲劳强度有很大的影响。①转速;②载荷;③工作温度;④环境介质;⑤润滑状况。
A. ①②③
B. ②③④
C. ①②③④
D. ②③⑤
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零件的表面状态是指零件表面的( )等。①粗糙度;②加工质量;③形貌;④应力状态;⑤成分和性能的变化。
A. ①②④
B. ①④⑤
C. ①③④
D. ②③⑤
零件材料的疲劳强度的大小受到内部因素的影响,主要指零件的( )等。①材料成分;②毛坯缺陷;③表面应力状态;④应力集中;⑤表面加工质量。
A. ①②③
B. ①③⑤
C. ①②③④
D. ①②④
I haven't been to New York before and_______.
A. neither has my sister
B. neither my sister has
C. I has not loo
D. my sister has not also
Never____ such a good boss before I came to this cotmpany.
A. do I meet
B. had I met
C. I met
D. I had met