根据句意和所给的首字母提示，补全句子中的单词。

1. If there were more trees on the earth, there would be l____ pollution.

2. I don't like eating lemon. It t____ too sour.

3. The injured people were taken to hospital i____ after the accident.

4. Look, the expression on his face s____ that something bad must have happened to him.

5. According to an ancient Chinese legend, the emperor Shen Nong d____ tea.

《中 * * 关于制定国民经济和社会发展第十一个五年规划的建议》提出，“十一五”期间，我国经济与社会发展要坚持( )的原则。

A．“五个必须”

B．“六个必须”

C．“七个必须”

D．“八个必须”