当to do不定式作宾语补足语
1、具体结构为:主语+谓语+宾语+动词不定式
例如:The teacher urged his students to prepare for the exam.
老师劝他的学生准备考试。
Their help enabled me to finish the work with ease.
他们帮助我,使我能够顺利地完成工作。
2、当动词不定式做make, have, let, hear, see, feel等动词宾语的补足语,要省略“to”
例如:My father will probably have Tom paint the house green.
我爸爸很可能叫汤姆把房子漆成绿色。
I felt my heart beat violently.
我感觉到自己的心跳得很厉害。
当to do不定式作目的状语
1、具体结构为:in order/so as + 动词不定式
例如:He must work very hard in order to support his large family.
他必须拼命工作以养活他的大家庭。
Listen carefully so as to follow the teacher.
要仔细听才能听懂老师讲的课。
2、具体结构为:be used + 动词不定式
例如:The book is used as a reference book.
这本书被用来做参考书。