前列腺素来源于（）.
A.垂体前叶
B.垂体后叶
C.下丘脑
D.生殖器官
E.前列腺
参考答案：D
This building is ___ that one.
A．three metres higher than
B．higher three metres than
C．so high as
D．twice high as
小车变幅机构载重小车运行到最小和最大幅度时，卷筒上两根钢丝绳的圈数均不得小于（）圈。
A.1
B.3
C.2
D.4
