可控硅是可控整流器、逆变换流器、无触点交流开关的主要器件,具有()、()、无电火花等优点。
参考答案:调节方便;开断迅速。
The old man has two sons, __________ lives with him, so he has always felt lonely since his wife’s death.
A.both of them
B.both of whom
C.neither of them
D.neither of whom
发生过敏性皮疹怎么处理?