题目

 Some of the doctors are paid almost           as the nurses. A. twice as much       B. much as twice     C. as much twice       D. as twice much    答案：A起重机用20s 的时间将重物吊起，整个过程中做的功是20000J，在此过程中起重机的平均功率是（　　）A．200WB．500WC．1000WD．2000W