风力发电机的组成：（）、（）、（）和（）。
参考答案：机舱；风轮；塔架；基础
Hangzhou is ______ a beautiful place ______ almost everyone enjoys it very much. [ ]
A. so; that
B. such; as
C. such; that
D. so; as
如果x2+xy=2，xy+y2=﹣1，则x2﹣y2= _________ ，x2+2xy+y2= _________ ．
