图甲、图乙分别是一个反射弧及其部分结构放大模式图。请回答问题： 图乙所示结构称为（）

阅读理解。

Jim: Let's play computer games.

Peter: That sounds good. Where's your computer?

Jim: I don't have a computer. Do you have a computer?

Peter: No, I don't. But I have a TV. Let's watch TV.

Jim: No, it's boring. Let's play tennis. I have a tennis racket.

Peter: Good. Where is it?

Jim: On the sofa. Do you have a racket?

Peter: No, I don't. Does your brother have a racket?

Jim: Yes, he does. And he has tennis balls.

1. Does Jim have a computer? ________ 　　

A. He has no computer.

B. He has two computers. 　　

C. Yes, he does.

D. No, he doesn't.

2. Jim has a racket. Where is it? ________ 　　

A. It's on the sofa.

B. It's near the sofa. 　　

C. It's behind the sofa.

D. It's under the sofa.

3. Does Peter have a tennis racket? ________ 　　

A. Yes, he does.

B. He has a tennis racket. 　　

C. He has two tennis rackets.

D. No, he doesn't.

4. Does Jim have a tennis racket? ________ 　　

A. Yes, he does.

B. No, he doesn't. 　　

C. He has two tennis rackets.

D. He doesn't have a tennis racket.

5. Does Jim's brother have a tennis racket? ________ 　　

A. He doesn't have tennis balls.

B. Yes, he does. 　　

C. No, he doesn't.

D. He has tennis balls.

实验表明：密度大于液体的固体球，在液体中开始时是竖直加速下沉，但随着下沉速度变大，其所受的阻力也变大，到一定深度后开始匀速下沉。

下表是某兴趣小组在探究“固体球在水中竖直匀速下沉时的速度与哪些量有关”实验时得到的数据记录(水的密度ρ_水=1.0×10³kg/m³)

（1）固体球在水中竖直匀速下沉时受到的力_______(填“是”或“不是”)平衡力；若固体球的半径为0.5×10^-3m，密度为2.0×10³kg/m³，则此球匀速下降时所受到的浮力F_浮与阻力f的大小关系为F_浮_______f(填“大于”“等于”或“小于”)．

（2）由第1、2、3三组数据可知：密度相同的固体球在水中匀速下沉的速度与固体球的___________ 成正比．

（3）若固体球的半径为1.5×10^-3m，密度为3.0×10³kg/m³，则其在水中匀速下沉的速度是______m/s。

（4）对于固体球在水中从静止开始竖直下沉的过程，四位同学描述出了重力对固体球做功的功率与其下落时间关系的P－t图像如图所示，其中描述正确的是：                       。

沉香含（）

A.果糖

B.小檗碱

C.鞣质和黄酮类

D.皂苷

E.白木香酸及白木香醛

渐开线齿轮基圆上的压力角为( )

A．20°
B．0°
C．小于分度圆上的压力角
D．10°

转化器采用低温触媒，降低了反应的温度，提高了系统的转化率，改变了反应的平衡状态和混合气体的平衡组成。