售货员：顾客：服务A．董事长：经理：服从 B．老师：学生：教育 C．政府：官员：领导

The man pulled out a gold watch, ______ were covered with some small diamonds. [ ]

A. the hands of them

B. whose the hands

C. the hands of which

D. of which hands

典型麻疹的出疹顺序？

I have lost one of my gloves. I _____ it somewhere.

A．must drop

B．must have dropped

C．must be dropping

D．must have been dropped

土壤中养分含量主要指土壤有机质和（ ）、磷、钾。

A．铁

B．氮

C．钙

效率是指水泵的有效功率与（）之比值。

A、轴功率

B、输出功率

C、扬程

D、转速