5. Language is a social and cultural 　　　　(现象).　

4. A good education should not just be a p　　 　of the rich.　

3. Most p　　 　feel nervous before they go on stage.　

2. He was found guilty and c　　 　to death.

1. After months of overworking, Jack was suffering from m　　 　and physical exhaustion.　

4. 解析：选C。推理判断题。根据最后一段“..., but many technical problems still must be cleared up on the way to this wonderful future”可知，还有很多技术问题需要解决，才能实现延长人类生命的目的。

3. 解析：选D。推理判断题。根据第二段“But the upper limits will be broken ..., people will be able to take medicine to repair their organs”可知，医药将能够修复人的器官使人活得更长。

2. 解析：选A。推理判断题。根据第二段“But the change in medicine can be the real technological event of our times”可以推断出,医药的改变是我们这个时代发展最大的技术。

20. 解析：选C。此处表达为：原来做的是一个“可怕的”梦。

19. 解析：选B。由文意可知，身体的剧烈晃动导致自己从睡梦中“醒”来。