根据句子意思，用括号中所给汉语提示或英语单词的适当形式填空。

1. You must keep it as a _____. It's only between you and me (秘密).

2. They taught _____ how to chat online when they were 8 years old (他们自己).

3. Kitty likes reading books _____ her sister likes watching TV (然而).

4. The government always _____ enough food and clothes for the people in poor areas (提供).

5. The _____ of such a good friend made us all sad the whole day (丧失).

6. He was badly ill yesterday, and he is even _____ today (bad).

7. As we all know, swallows fly to _____ countries in summer (north).

8. He is a _____ boy. He often tells lies and no one likes being friends with him (honest).

9. We always have a great time _____ with each other during lunchtime (chat).

10. What a _____ cold day it was yesterday! No one went out for a walk (terrible).

影响化学反应速率的外界条件是（1）反应物颗粒大小（2）温度（3）浓度（4）使用催化剂，其中正确组合的是（　　）

A．全部

B．（2）（3）

C．（4）

D．（2）（3）（4）