水泵水泵不上水的原因可能是（）。
A、水位高
B、水位低
C、淤泥将底阀淹没
D、水仓有杂质
参考答案：C
His health is ______improving. I'm sure he will come back to work soon.
A．gradually
B．frequently
C．fluently
D．finally
下列化学消毒剂哪-'种属于高效消毒剂
A．含氯消毒剂
B．0.5%碘伏
C．洗必泰酒精
D．75%酒精
E．新洁尔灭
