解放军文职考试：不定式定义

　　不定式定义:(语态)动词和参与此动作的主语之间关系的一个术语。当主语是动作的发起者(或之一)时，称为主动语态;

　　如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者，不定式一般要用被动语态形式。如：

　　It's a great honour to be invited to Mary's birthday party.(不定式作主语是被动语态to be invited是被邀请)

　　It was impossible for lost time to be made up.(不定式作主语)

　　I wish to be sent to work in the country.(不定式作宾语)

　　Can you tell me which is the car to be repaired?(不定式作定语)

　　He went to the hospital to be examined.(不定式作状语)

    在There be结构中，修饰主语的不定式可用被动，也可用主动。如：There are still many things to take care of (to be taken care of).但有时两种形式表达的意思不同，如：There is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)