晶体中原子的结合力类型有哪些？
参考答案：晶体中原子结合力的类型有：离子型，共价型，金属型及范德瓦尔斯结合力。
They were all pleased with _____ them. [ ]
A. what you said
B. what did you say
C. what you had told
D. what you had spoken
3kV及以上应装失步保护的电动机为( )。
A．1MW及以上异步电动机； B．2MW及以上异步电动机；C．同步电动机； D．2MW及以上的同步电动机。
