在英语句子里，几个修饰语叠用的时候，有一定的排列秩序。修饰语在句子中的位置错了，或排列乱了，便有麻烦，甚至意思也会因此改变，有时连语气也不通畅。

不定式动词（the infinitive）或不定式动词短语（the infinitive phrase）的功能之一是修饰动词。这种具副词功能的不定式动词或短语，和分词短语一样，可以在句子中发挥不同作用，包括“目的、结果、原因、比较”。

　　Ⅰ表示目的，如：
　　● To learn a language well, one must make great efforts and work with tenacity.
　　● To prevent war, big or small, it is important to promote international understanding.
　　● Zhiqiang came to my office to ask a question.
　　● The warden walked around the building to see that nothing went wrong. 　　表示“目的”的不定式动词短语可以在句首，也可以在句尾。在句首时，可以加上“in order”；在句尾时，可以附以“so as”，如：
　　● In order to win the table-tennis match, the players practised day and night.
　　● Betty worked very hard so as to catch up with the rest of the class.

　　Ⅱ表示“结果”，如：
　　● Indonesia beat Denmark to take the first place in the badminton tournament.
　　● Sam passed the final examination to qualify for the next phase of study.
　　表示“结果”的不定式动词短语出现在句尾，而且经常以预料不到的情况出现，如：
　　● After the short meeting, they separated, never to see each other again.
　　● Li Qi rushed to the bus station as fast as he could, only to find the last bus already gone.

　　Ⅲ表示“原因”，如：
　　● I was really a fool not to listen to you at that critical moment.
　　● No gambler wins in the end and you would do well to avoid gambling of all forms.

　　Ⅳ表示“比较”，如：
　　● She opened her lips, as though to speak.
　　● Her friend looked at him, as if to have something important to tell him.

　　必须注意的是，含“比较”意思的不定式动词或短语前面要用“ as if ”或“as though”引导。

　　除了直接修饰谓语动词之外，不定式动词或短语还可以和介词“ with, for”连用，如：

　　● With nobody to help, the poor man worked late into the night.
　　● The police removed the road block for the cars to pass.
　　● With little money to be used, Judy could not buy any more expensive things.
　　● For a lesson to be fruitfully taught, the teacher must make thorough preparations before going to class.
　　● For such a scheme to work well, the staff concerned have to be devoted and effective.
　　● With limited power to be exercised, the new manager could get nowhere.