已知a=$\sqrt{0.3}$，b=2^0.3，c=0.3^0.2，则a，b，c三者的大小关系是（　　）

电源的电动势和内电阻的测量是高中阶段重要的实验．

在某次实验中，实验室可以提供的器材有：

a．待测电池：电动势E（约3V）、内电阻r（约1Ω）

b．电流表：量程500μA，内阻为400Ω

c．电流表：量程1A，内阻约0.2Ω

d．滑动变阻器：阻值0～600Ω，额定电流0.5A

e．滑动变阻器：阻值0～20Ω，额定电流2.5A

f．定值电阻7600Ω

g．定值电阻600Ω

如图，半径为4的球O中有一内接圆柱，当圆柱的侧面积最大时，球的表面积与该圆柱的侧面积之差是____ 

把下面的图片与所给的描述对号入座。
A        B          C 
D                E
____ He is of medium height and build, with two small eyes. He is a pop singer. And he likes playing basketball very much. He is very popular with young people.
____ He is short and of medium build. He has short black hair. He is a funny actor.
____ She is heavy. She has short brown hair. She always wears glasses. She sings very well.
____ He is very tall and has short black hair. He is a basketball player, and he plays it very well. Now he is a college student in Shanghai Jiaotong University.
____ She is thin, with long black hair and big eyes. She is a movie star. She is in the play "Palace", and she is very popular with young people.