题目

1.I am busy now,so I can’t help ______ the machine.A.repair B.to have repaired C.repairing 实在不知道怎么选a
2..The boy seated himself in the corner with his back ______ to his father.
A.turning B.to turn C.to be turned D.turned为什么不能选turning而要选turned,这里有要表过去的意义吗
3..______ the room,a letter was laid on the ground.
A.Entering B.Having entered
C.He entered D.Mrs Green entering觉得前三个选项都不对,因为主句的主语是letter,但是对于选d的用法也不明白
4.______ to nuclear radiation,even for a short time,may produce variants of genes in human bodies.
A.Being exposed B.Having exposed
C.Exposed D.After being exposed 这个题更让我迷糊,主句的主语没找到,还是说主句的主语在分词短语里,是什么在核辐射下暴露了在短时间内就产生了人体基因的变异?
5.----Will you please tell us how you can seize the robbers?
----I will spend a whole week ______ in your room to wait for their coming.
A.locking B.to lock C.locked D.being locked
不明白为什么选c,即使是被锁,为什么不能是d

提问时间：2020-12-22

答案

1. 根据题意,应该是我很忙,不能帮忙修理这台机器了.help (to) do sth 的意思是：帮忙做某事.此题容易误认为是考察can’t help doing(忍不住做某事).
2. 这个题的关键是理解短语turn one’s back to sb. “背对某人” .with+ n.+ 非谓语的选择技巧是看with后边的名词和要填的非谓语之间存在主动还是被动关系,因为his back是turn这一动作的宾语,也就是说他的背是“被转过去”的,故用过去分词作补语.再如：The boy sat there with his eyes closed. 男孩坐在那里,紧闭双眼.眼睛是“被闭上”的,所以用“closed”作补语,说明他们的状态.
3.. Mrs Green entering the room是独立主格结构,完整的句子应该是：When Mrs Green entered the room. 因为本题的后半部分是个独立的句子,而前半部分缺少连词,故不能选C一类的完整简单句,只能选含有非谓语的独立结构.再如：
The weather being fine, we decided to go fishing. （由于）天气不错,我们决定去钓鱼.独立主格的特点是逗号前后两部分的主语不同.
4．Being exposed to nuclear radiation 是这个句子的主语,中间的插入语even for a short time 可以不用管.may produce是谓语, variants of genes in human bodies是宾语.选项B、C、D在句首时都是作状语的,不能做主语,所以不对.
5. 此题中的lock是及物动词,考查了lock sb. in some place. ,而且lock是短暂动词,这一点很重要.如果选being locked 表示正在被锁,而前边的时间状语是一整周的时间,不可能用这么长时间来完成“锁上”这个短暂动作,您能明白吗?
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