5)不定式作状语

　　不定式结构在句中作状语通常都能转换为限制性状语从句。

　　例如作原因状语：1.They are quite surprised to see the great changes taking place in the area.2.They are quite surprised because they see the great changes taking place in the area.3.He was lucky to arrive before dark.4.He was lucky because he arrived before dark.

　　作目的状语：1.She raised her voice to be heared better.2.She raised her voice so that she could heard better.3.We went via Heidelberg to miss the traffic jam.4.We went via Heidelberg so that we could miss the traffic jam.

　　作结果状语：1.The French football team played so successfully as to defeat the Brazilians.2.The French football team played so successfully that they even defeated the Brazilians.3.He got to the station only to be told the train had gone.4.He got to the station and was told that the train had gone.

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　　不带to的不定式的使用

　　动词不定式通常带to，但在有些搭配中不带to，在另一些搭配中可带to可不带to。归纳起来，以下情况下使用不带to不定式：

　　1)在can/could，/may/might，will/would，shall/should，must，need，dare等情态动词之后，动词不定式不带to。

　　2)在表示感觉意义的动词，如see初中英语语法总结，feel，watch，notice，smell，hear，observe等后，或是表示“致使”意义的动词，如have，let，make等后，动词不定式不带to。例如：1.I often heard him say that he would study hard.2.I must have him see his own mistakes.

　　但是，当这类结构转换为被动语态时，后面的不带to不定式一般转换为带to不定式。

　　例如：1.He was often heard to say that he would study hard.2.After he had finished speaking，he was made to answer innumerable questions.

　　3)在动词help之后可用不带to的不定式，也可用带to的不定式。例如：1.Help the old lady(to)carry the heavy box.

　　4)在had better，would rather，may/might as well，rather than，can not but等搭配之后初中英语语法总结，动词不定式也不带to。例如：1.Unless you feel to ill to go out，I would rather not stay at home tonight.2.She could not but criticize his foolish behaviour.

　　5)在make do，make believe，let drop，1et fall，1et fly，let slip，let drive，let go off，hear say，hear tell，leave go of等固定搭配中，用不带to的动词不定式。例如：1.They let go of the rope.他们松开了绳子。2.John let fly a torrent of abuse at me.约翰朝我痛骂了一顿。3.I've heard tell of him.我听说过他。4.Some of the faculty were let go for lack of the students.由于生源不足，一些教职员工被解雇了。

　　6)在介词but初中英语语法总结初中英语语法总结，except之后，如果其前有动词do的某种形式，其后不定式一般不带to，反之则必须带to，表示“不得不初中英语语法总结，只能”。例如：1.He will do anything except work on the farm.2.There was nothing left for the enemy to do but surrender.3.The spy was both hungry and cold;there was nothing left for him but to give in.4.I had no choice but to wait till it stopped raining.

　　下面一些短语是固定搭配，不带to：can not help but，can not choose but，can not but，do nothing but，have nothing to do but。例如：I can not but admire his courage.

　　如果上述句中有do，to省略：I did nothing but watch TV last night.

　　如果是下面一个固定搭配，就带to：I have no choice but to give up my idea.

　　7)紧跟在why或why not之后的动词不定式总是不带to。但是，紧跟在who，what，which，whether等连接词后的不定式带to。例如：Why stand up if you can sit down?Why not ask your teacher when you don't understand the meaning?You needn't decide yet whether to study arts or science.