已知幂级数，则所给级数的收敛半径R等于（）。 A.1/b B.1/π C.1/a D

治疗耳聋实证，应选用以下哪组经脉为主()

A.足少阴、手太阳经穴

B.足少阳、手少阳经穴

C.足少阴、手少阴经穴

D.足少阳、手少阴经穴

E.足少阴、手少阳经穴

用所给动词的适当形式填空。

1. It ______(take) me over an hour to get there yesterday.

2. Andy was not very tired, so he decided ______(not stay) at home.

3. Don't ______(knock) the books off the desks.

4. He was ill because of _______(work) all day and all night.

5. The mother made the poor girl _______(play) the piano for eight hours a day.

6. Thank you for ______(agree) to let me join in the party.

7. Would you please ______(show) me around your school?

8. We always have a great time ______(play) games after school.

9. Taking a bus is much faster than ______(walk).

10. He thought about how______(solve) the safety problem.

已知命题:①若点P不在平面α内,A,B,C三点都在平面α内,则P,A,B,C四点不在同一平面内;②两两相交的三条直线在同一平面内;③两组对边分别相等的四边形是平行四边形.其中正确命题的个数是(　　)

A．0

B．1

C．2

D．3

直接转换技术的DR中应用的转换介质是（）.

A.影像板

B.增感屏

C.碘化铯

D.非晶硒

E.非晶硅

为了限制故障的扩大，减轻设备的损坏，提高系统的稳定性，要求继电保护装置应具有（）。

A.灵敏性

B.快速性

C.可靠性