解析　quit放弃，戒除；decline下降；prevent阻止，预防；reserve预定，保留。句意为：医生们正在研究当人们戒烟的时候身体上会发生什么变化。根据句意可知A正确。

5．_________ made her surprised was the news______ our volleyball team won the championship _________was true.

A．What；that；that B．What；that；which

C．That；that；that D．What；which；that

答案　A

解析　句意为：使她感到惊讶的是，我们的排球队获得冠军的消息是真的。第一空引导主语从句，且在从句中作主语，用what；第二空引导表语从句，从句中不缺成分，故用that；第三空引导同位语从句，从句中不缺成分，故用that。

6．More and more people began to realize that nothing could be equal to the_______ of parents for their children in the world.

A．appreciation B．intention

C．invitation D．affection

答案　D

解析　句意为：越来越多的人开始意识到，在这个世界上没有什么能比得上父母对孩子的爱。appreciation感激；intention打算；invitation邀请；affection热爱。由句意可知选D项。

7．He passed his college entrance exam，thus_________ his and his parents' goal.

A．realized B．to realize

C．having realized D．realizing

答案　D

解析　因realize与其逻辑主语he之间为主动关系，故用现在分词短语作结果状语，故选D。

8．Every evening after dinner，if not______ from work，I will spend some time walking my dog.

A．being tired B．tiring

C．tired D．to be tired

答案　C

解析　本句含有if引导的条件状语从句的省略形式，还原后应为if I am not tired from work，根据省略的原则，故选C项。

9．In the yard was an old man telling stories，_________ with quite a few children him.

A．surrounding B．surrounded

C．to surround D．being surrounded