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1. Everyone knows that _______ is dangerous to play with fire, but _______ is difficult is to prevent children from playing with fire.
A. it, it B. what, what
C. it, what D. what, it
【陷阱】很容易误选B，认为两空均考查形式主语。
【分析】最佳答案是C，第一空填形式主语，真正的主语是其后的不定式 to play with fire。第二空填 what，what is difficult 是主语从句，注意 what is difficult 后的谓语动词 is。请做以下类似试题：
(1) I know ______ is important to know my own limitations, but _______ is difficult is to help others to know their own limitations.
A. it, it B. what, what
C. it, what D. what, it
(2) Yes, ______ is difficult to find a job nowadays, but _____ is more difficult is try to find such a job with a high salary but little things to do.
A. it, it B. what, what
C. it, what D. what, it
2. I dislike _______ when others laugh at me in public or think poorly of me behind.
A. that B. those
C. it D. them
【陷阱】几个干扰项均有可能误选。
【分析】最佳答案是C，因为在通常情况下，like 是及物动词，其后应有宾语(句中 it 即为其宾语)。句中的 when 从句不是宾语从句，而是时间状语从句，其中的 when 的意思是“当……的时候”。其实，也有的词典将 I don't like it when (if) … 作为一个句型来处理。能这样用的动词不多，主要的有enjoy, like, dislike, love, hate, prefer, appreciate等表示喜好的动词。
She won't like it if you arrive late. 她不喜欢你迟到。
He hates it when people use his bike. 他讨厌别人用他的自行车。
请做以下类似试题(答案均选 it)：
(1) I hate _______ if people say such things in public.
A. that B. those
C. it D. them
(2) I'd prefer _______ if I didn't have to get up early on Sundays.
A. that B. such
C. it D. which
(3) I would appreciate _______ very much if you could give me some suggestions.
A. this B. that
C. it D. you
3. I've no idea. I just pretended nobody was at home, so I didn't ask who _______ was.
A. he B. that
C. she D. it
【陷阱】容易误选A或C。
