( )不是超声波探伤的缺点。A．判断缺陷性质直观性差 B．对缺陷尺寸判断不够准确

— Does Linda have a baseball?

— ______. But she has a basketball. [ ]

A. Yes, she is

B. No, she isn't

C. Yes, she does

D. No, she doesn't

Fe³⁺/Fe²⁺电对的电位在加入HCl后会降低．加入邻二氮菲后会增加。

分子量大致相近的不同烃类，其辛烷值以（）最低。

A.环烷烃

B.正构烷烃

C.芳香烃

D.异构烯烃

吸、送风机振动的原因有哪些？

马神甫事件，“亚罗号”事件，马嘉理事件