9. 解析:选B。后半句句意为：我已经多年不吸烟了。根据句意可推知应用否定回答。

8. 解析:选D。考查状语从句的用法。句意为：一旦环境遭到破坏，就需要好多年才能恢复生态系统。even if 即使；if only 但愿，要是……就好了；while 当；once 一旦。

7. 解析:选B。句意为：为了向来访主席表示敬意而举办了一场大型晚会。in honour of 为了表示对……的敬意；in memory of 为了纪念；in favour of 支持，赞同；in need of 需要……。

6. 解析:选D。当would rather后接从句时要用虚拟语气，这时谓语动词常用一般过去时。

5. It was wise of my son to invite several classmates to help him.

?提升练习

4. It was not until many years later that I knew the secret.

3. How amazing the Great Wall is!

2. At that moment, in came a beautiful lady.

B.1. left　 2. stay　 3. remaining / left

C.1. pity　 2. mercy

D.1. were; aware that　 2. recommend

3. contributes to　 4. go through　 5. remind; of

7. precious　 8. recommend　 9. exposed　 10. length