章振邦《新编英语语法》Lecture 19-20不定式教学课件.ppt

19.1 Forms of the infinitive Grammatical forms – The infinitive has no tense distinctions, nor person or number contrasts. But they can be passive and take the simple (to write), progressive (to be writing), perfective (to have written) and perfective progressive (to have been writing) forms. A negative infinitive is formed by adding not or never immediately before the infinitive sign to. The passive infinitive is formed by to be +ed-participle or to have been + ed-participle. 2) To-infinitive and bare infinitive There are two types: to-infinitive and bare infinitive. The bare infinitive is just the infinitive without to, which is identical in form with the base of the verb. 19.2 Notes on the use of the infinitive sign 1) The infinitive sign used alone: To avoid repetition, the infinitive sign can sometimes be used alone, i.e. the base in the to-infinitive can be omitted, even together with its complementation, especially in informal style, e.g.: George says he is going to leave Shanghai, but I don’t think he really wants to. We should like Jane to get a good degree, but we don’t really expect her to. If the base of the infinitive is the verb be or have, it should be retained, even though its complementation is omitted, e.g.: A: Are you the manager? B: No, I don’t want to be. In some contexts, both the to-infinitive and its complementation can be omitted so that no trace remains of the infinitive, e.g.: I’d like to do it now, but I haven’t got the time (to do it). You will make it if you try (to). 2) Ellipsis of the infinitive sign: When two to-infinitives are coordinated by and or or, the second to is usually omitted, e.g.: She asked me to telephone or wire to her on Monday. When there is a contrastive meaning, the second to must be retained, e.g.: To be or not to be, that is the question. The infinitive sign cannot be omitted if there is no coordinator between the coordinate infinitives, e.g.: Please go to the seaside to sw