临床判断气胸类型的主要依据是（）。
A.呼吸困难的程度
B.X线胸片检查
C.动态胸腔内测压
D.诱发因素
E.有无休克
参考答案：C
The old lady had a son and two daughters，________treated her well，which made her very sad.
A．no one of whom
B．none of whom
C．neither of them
D．none of them
当交流电路中有非线性元件时，就会产生非正弦电流。（）
