根据句意及首字母提示写出所缺单词。

1. People in Korea are supposed to b_____ when they meet for the first time.

2. In China people often s_____ hands with each other when they meet for the

first time.

3. My classmates are m_____ boys.

4. You're supposed to k_____ when you meet people for the first time in Brazil.

5.  When you are i_____ for a party, you should arrive a little earlier in my

country.

如图，利用培养皿探究氨气的性质．实验时向NaOH固体上滴几滴浓氨水，立即用另一表面皿扣在上面．下表中对实验现象所做的解释正确的是（　　）

A．A

B．B

C．C

D．D