曲线yx2和y2x所围成的平面图形绕x轴旋转一周后，所形成的-优题课

曲线y=x²和y²=x所围成的平面图形绕x轴旋转一周后，所形成的旋转体的体积为（　　）

A．

B．

C．

D．

科目数学题型选择题难度中等

知识点：微积分的产生──划时代的成就

If I hadn't been faced with so many barriers，I ______ where I am．（　　）

A．	won't be	B．	wouldn't have been
C．	wouldn't be	D．	shouldn't have been

There will still be lots of challenges if we are to ______ garbage in a short time．（　　）

clarify

justify

satisfy

classify

Instead of getting down to a new task as I ______， he examined the previous work again．（　　）

A．	had expected	B．	have expected
C．	would expect	D．	expect

It is not a problem ______ we can win the battle；it's just a matter of time．（　　）

whether

why

when

where

Building such a bridge over the bay was ______，but the local government made it within two years．（　　）

A．	a wet blanket	B．	a piece of cake
C．	a dark horse	D．	a hard nut to crack