补全对话。 根据对话内容， 在空格中填写一个句子， 使对话完整、正确。

A. Do you think I can pass the PE test?

B. 1______. You've been exercising for quite a long time.

A. Yes, but I'm still worrying about that.

B. 2______. You can succeed this time.

A. 3______. You know, besides exercising every day. I also eat on diet.

    It's possible that I've lost some weight.

B. Yes, 4______. people are likely to lose weight when they exercise more and eat less.

A. All right. 5______. Bye-bye.

B. Bye-bye. Good luck.

如图所示，带正电的小球穿在绝缘粗糙直杆上，杆倾角为θ，整个空间存在着竖直向上的匀强电场和垂直于杆斜向上的匀强磁场，小球沿杆向下运动，在a点时动能为100J，到C点动能为零，而b点恰为a、c的中点，在此运动过程中（　　）

A．小球经b点时动能为50J

B．小球电势能增加量可能大于其重力势能减少量

C．小球在ab段克服摩擦所做的功与在bc段克服摩擦所做的功相等

D．小球到C点后可能沿杆向上运动