塑性材料的下列应力状态中，（）种最易发生剪切破坏。
A.
B.
C.
D.
参考答案：B
— What's wrong with your iPad? The sound _____ is not clear.
— Yes. It has been broken for some time. [ ]
A. come out
B. coming out
C. to come out
D. came out
原子核的组成是（）
A.质子和光子
B.质子和电子
C.质子和中子
D.中子和电子
E.中子和光子
