甲现年16岁，在电器维修部工作，收入较高，但仍与父母同住。甲购买一只价值2万元的钻戒

图甲是利用砂摆演示简谐运动图象的装置，当盛砂的漏斗下面的薄木板被水平匀速拉出时，做简谐运动的漏斗漏出的砂在板上形成的曲线显示出砂摆的振动位移随时间变化的关系。第一次以速度匀速拉动木板，图乙给出了砂摆振动的图线；第二次使该砂摆的振幅减半，再以速度匀速拉动木板，图丙给出了砂摆振动的图线。由此可知，砂摆两次振动的周期和以及拉动木板的速度和的关系是

A．

B．

C．

D．

装配图的尺寸一般应标注()。

A．装配尺寸

B．定位尺寸

C．安装尺寸

D．性能规格尺寸

E．定形尺寸

F．外形尺寸

根据句子意思，用括号中所给单词的适当形式填空。

1. Our school becomes quiet and _______ (peace) after children leave.

2. Sandy organized a charity show _______ (success) last year.

3. Bill was feeling sad. He told me about his _______ (happy).

4. ______ (sleep) in a blue room is good for your mind and body .

5. Simon just forgot when ______ (meet) his friends

6. Wearing red can help when you are having difficulty ______ (make) a decision.

7. You'd better give up _______ (smoke), it's bad for your health.

8. A year is _______ (divide) into 12 star signs in western countries.

9. Andy is _______ (energy) enough to be a leader.

10. It is silly of you _______ (not forgive) others for their faults.

金属导体中定向移动形成电流的是______；在酸、碱、盐的水溶液里定向移动形成电流的是______．

工作场地昏暗，无法看清（）、（）和（），司机拒绝吊运。