如图所示，敲响右边的音叉，左边完全相同的音叉也会发声，并且把泡沫塑料球弹起，该实验能说明那些问题？请你写出两个：

（1） ____

（2）____

青藏高原终年雪山连绵，原因是（ ）

先人后己      鞠躬尽瘁      心潮澎湃

①读了《桥》这篇课文，我非常感动，此刻的心情可以说是____。文中的“老汉”在关键时刻____，行为十分感人。他为人民____，犹如一座丰碑，永驻人们心中。

迫不及待      辛辛苦苦      一声不吭

②____的瑞恩突然说：“那我来攒钱买钻井吧！”

③瑞恩把____挣来的70元钱交给了募捐项目的负责人。

④6岁的瑞恩一放学，就____地冲进家。

根据首字母提示补全对话

(An old woman is standing at the side of the road, near the traffic l____ . Liu Mei is on her way to the cinema, but she stops. )

Woman: Oh, dear! What shall I do?

Liu Mei: What's the m____ , Granny? Can I help you?

Woman: I'm on my way to see my h____ . He's ill in hospital.

Liu Mei: Which hospital?

Woman: I don't know! The address was on a p____ of paper, but I can't find it now.

Liu Mei: Is it in your pocket? M____ you put it there.

     (The woman finds the paper.)

Woman: Could you tell me how I can get to the hospital? I don't k____  the way. Which is the way to the hospital?

Liu Mei: Go down this street until you r____ the second traffic lights. Turn right; at the end of the r____ you'll see the hospital. It'll take you about half an hour.

Woman: Half an hour? That's too l____ ! Is there a bus?

Liu Mei: Yes, the No. 72 bus will take you there. There's a stop right o____ the hospital. I'll go with you.

Woman: How kind you are! Thank you.