当原子核处于外磁场中时，核外电子运动要产生感应磁场，核外电子对原子核的这种作用就是（）.
参考答案：屏蔽作用
构成物质的粒子有 _________ 、 _________ 、 _________ ，
如水是由 _________ 构成的，铁是由 _________ 构成的，氯化钠是由 _________ 构成的．
根据句意及首字母写出单词。
1. Jean sends me a p__________.
2. Do you know the a__________ to this question?
3. What's your telephone n__________?
4. Here's my ID c__________.
5. This is a c__________ game. I like it.
6. His p_________ are workers. They work in a factory.
7. My uncle's children are my c__________.
8. This is my f __________ photo. These are my parents and this is me.
9. T_________ for your help!
10. She is Mr Green's d__________. Her name is Mona.
