1、Unit 4重点句子解析1. I havent decided which one to write yet.句中的which one to write是“疑问词 + 不定式”结构用在动词decide后作宾语。不定式可以与疑问词who, what, which, when, how, where 等连用，构成不定式短语，在句中作主语、表语、宾语或宾语补足语等。如：Where to buy this kind of computer is a problem. 到哪里去买这种计算机是一个问题。I really dont know what to do. 我的确不知道该怎么办了。The quest
2、ion is how to get there. 问题是怎么到那里去。Can you tell me which one to choose? 你能告诉我该选择哪一个吗？2. If you think about it, it can take a long time to come up with the right words.这句话中的if you think about it是条件状语从句，表示前提，短语think about意为“考虑”；第二个it是形式主语，动词take表示“花费”，真正的主语是后面的不定式to come up with the right words，短语come
3、 up with意为“想出”。 如：We dont believe they can keep up with us. 我相信他们是不会赶上我们的。3. Describe your topic in two words. 介词in 在这里表示方式，后接名词、代词、V-ing形式，多用在动词后作状语。如：Can you say these words in another way? 你能用另一种方法说出这些单词吗？4. The man looked at the gold axe, knowing it wasnt his.句中的knowing it wasnt his是现在分词短语作状语，表示
4、伴随状况。如：Mr. Zhang walked into the classroom, holding two books in his hand. 张先生手里拿着两本书走进了教室。5. He thought it must be the kings musicians passing by.情态动词must 加上动词原形表示肯定推测的含义。如：He wasnt in the classroom. He must play on the playground. 他没在教室里。他一定在操场上玩呢。情态动词cant加上动词原形表示否定推测的含义。如：She cant be in Washingto
5、n because I saw her here just now. 她不可能去华盛顿了，因为刚才我在这里还见到了她。6. Along with them came the spring.这是一个倒装句式，伴随状语along with them放在句首起强调作用，然后是谓语动词，最后是主语。如：Away with me went upstairs. 和我一起到楼上去了。7. We learned to write stories and poems this week.在下列动词后往往加不定式作宾语：want, hope, wish, like, begin, start, try, agre
6、e, know, learn, promise, refuse, decide等。如：She refused to leave with us. 她拒绝和我们一起走。My parents promised to buy a computer for me. 我的父母答应给我买一台计算机。8. I like reading stories, but I think they are very hard to write.系词be 加上形容词后再加不定式表示“很做某事”，其中的不定式作状语。如：English is easy to learn. Do you think so? 英语容易学。你认为这样吗？
