汽轮机寿命由哪几部分组成()
A.受到高温和工作应力作用而产生的蠕变损耗
B.受到交变应力作用引起的低周期疲劳寿命损耗
C.转子寿命
D.汽缸寿命
参考答案:A, B
The life of a professional tennis player is tough ________ you never seem completely free to do _______ you like --- even in the off-season.
A.when; what
B.because; that
C.as; whatever
D.when; whatever
用于获得字符串Str从第2个字符开始的3个字符的函数是( )。
A.Mid(Str,2,3)
B.Middle(Str,2,3)
C.Right(Str,2,3)
D.Left(Str,2,3