梯形的中位线长20cm，高为8cm，则梯形的面积为______cm2．
根据题意得
梯形面积=中位线×高=20×8=160（cm2）．
Not only _____ able to dance, but also _____ able to sing many English songs. [ ]
A. he was; he was
B. was he; was he
C. was he; he was
D. he was; was he
下列是电价管理的工作原则是（）。
A.统筹兼顾
B.重在研究
C.系统优先
D.重在应用
