杭州:西湖
A.长城:北京
B.无锡:太湖影视城
C.杭州:留园
D.青岛:趵突泉
参考答案:B
—Would you please tell me _____?— Sorry, you can turn to Mr Lee for help.
A.how long can man live without water
B.whether Yao Ming still played for Rockets
C.how I can keep myself safe from the flu
D.why did a serious accident happen
用一个动滑轮将400N的货物提高lm,所用的力是250N,则力所做的功是____J,有用功是____J,机械效率是____。