根据句意及首字母（汉语）提示，补全单词

1. My little brother is an e_________ boy.  He can do a lot of things without having a rest for many hours.

2. You can't take these books out of the reading room without the teacher's p_________.

3. Zhang Jian is outgoing.  He has a large _________(圈子) of friends.

4. Although the computer has a lot of advantages, it can't do _________(创造性的) job.

5. _________(打扰) others suddenly when they are talking is very rude.

实验室用大理石和稀盐酸反应制取二氧化碳，现用含4g碳酸钙的大理石与足量的稀盐酸反应．试计算：

（1）碳酸钙中钙、碳、氧三种元素的质量比是：______．

（2）碳酸钙中钙元素的质量分数．

（3）最多可制得二氧化碳多少克？