A. has left B. is to leave C. leaves D. is to be left
       
        6) As teachers we should concern ourselves with what is said, not what we think ____.(1997.6)
        A. ought to be said B. must say C. have to be said D. need to say
       
        7) Once environment damage ____, it takes many years for the system to recover.(1997.6)
        A. has done B. is to do C. does D. is done
       
        Explanation and Expansion
        A. 参考答案：1）C 2） B 3） B 4） C 5） D 6） A 7）D
        B. 评析
        ① 是否可用被动语态主要看谓语动词与句子主语之间的关系，如果是动宾关系自然用被动语态。
       
        ② 注意被动语态的各种时态构成，但四级考试中没有正误结构的判断，考生只需要根据上下文判断出该用什么时态即可。
       
        ③ 不及物动词不可能有被动语态，但及物动词也未必有被动语态，主要是看句子侧重表达的概念，如3题中wear表示眼镜的特点，不可用被动语态。在如：
        This kind of software sells well.
        It being too cold, the car wouldn't start.
        won't wouldn't表示"拒绝"谓语动词不用被动形式。
       
        ④ 注意含有情态动词的被动语态的结构，以及类似的结构，如have to be done, used to be done, be said to be done, be to be done。把握各种结构表示的意思。然后就是根据具体的上下文选择适当的情态动词或时态的问题。
        Self-practice
       
        好，刚才我们一起了解了被动语态的考查特点和解题注意事项，下面请同学们请做《语法分册》第六章 第四节 自我训练题。
       
        二、虚拟语气
         英语中的虚拟语气有4种，一种是条件句中的虚拟语气，一种是含蓄条件句中的虚拟语气，一种是名词性从句中的虚拟语气，还有一种是状语从句中的虚拟语气。其中虚拟时态的运用很大程度上和其所处的句型有关。95年以来，对虚拟语气的考查有28题之多，占词汇/语法总数的15.2%。下面我们也分四部分来看一下四级考试中虚拟语气的运用。
       
        1.条件句中的虚拟语气
        Test yourself
        在我们分析虚拟语气的考查特点也应对策略之前，还上请同学们先做做一下以下各题：
        1) If I hadn't stood under the ladder to catch you when you fell, you ____ now. (1999.1)
        A. wouldn't be smiling B. couldn't have smiled C. won't smile D. didn't smile
       
        2) ____ for my illness I would have lent him a helping hand. (19995.1)
        A. Not being B. Had it not been C. Without being D. Not having been
       
        3) ______before we depart the day after tomorrow, we should have a wonderful dinner party. (1997.1)
        A. Had they arrived B. Would they arrive C. Were they arriving D. Were they to arrive
       
        4) Jean doesn't want to work right away because she thinks that if she ____ a job she probably wouldn't be able to see her friends very often.(1996.1)