摘要：不定式是动作，它需要动作执行者。有时动作执行者是显表达，有时需要推定。大体有如下五种情形。

不定式是动作，它需要动作执行者。有时动作执行者是显表达，有时需要推定。大体有如下五种情形。

情形1：继承主干句的主语，如

【例句1】I was glad to see her. (我很高兴见到她。)

【例句2】Lucy was assumed to have left the day before. （人们认为露西前一天就离开了。）

【例句3】I want to go. （我想去。）

【例句4】I've come here to help you. (我是来帮你的。)

情形2：紧邻不定式的主干句宾语，如

【例句5】I want you to go. （我要你走。）

【例句6】The teacher made Jack rewrite the composition. (老师让杰克重写作文。)

【例句7】I'll have her copy the document right away. （我马上让她把文件复印一下。）

【例句8】I couldn't get her to understand the problem. (我无法让她理解这个问题。)

【例句9】I saw him cross the street. （我看见他过马路。）

情形3：用介词for明确给出，如

【例句10】We were waiting for the rain to stop. (我们在等雨停。)

【例句11】It's easy for an outsider to say what should be done in such a situation. （局外人很容易说出在这种情况下应该做什么。）

情形4：面向众生宣称的语境，可推断为people，we, one, 或you，如

【例句12】It is sometimes difficult to accept the truth. (有时很难接受真相。)

【例句13】The rules didn't specify who to talk to in case of an emergency. (规则没有规定在紧急情况下与谁交谈。)

情:5：由特定语境，由语境推断，如

【例句14】It must have been funny to see her in a tuxedo. (看到她穿燕尾服一定很有趣。)

【例句15】Nice to meet you. （很高兴认识你。）

【例句16】It would be a mistake to hire him. (雇用他将是一个错误。)

来源：美好教育