下列选项不属于晶闸管过电压保护措施的是（）。
A.交流侧保护
B.直流侧保护
C.整流主电路元件保护
D.缓冲电路保护
参考答案：D
In a physical change no new substance is formed，__________ in the composition of matter.
A．nor does any change take place
B．nor any change takes place
C．not any change takes place
D．either any change takes place
I haven’t read ____ of his books, but judging from the one I have read I think he’s a very promising writer.
A．any
B．none
C．both
D．either
