不带to不定式的十八种情况动词不定式通常带有符号to，叫做带to的动词不定式(infinitive with "to")，动词不定式有时不带符号to，叫做不带to的动词不定式(infinitive without "to")不带to的动词不定式通常有下面十八种情况：一、与助动词do连用构成谓语动词的否定、疑问和强调形式。
(1)He does not work in the factory.他不在这家工厂上班。
(2)Does she work here？她在这儿上班吗？(3)I did not see her yesterday.我昨天没有看见她。
(4)Did they take you home?他们把你送回家了吗？(5)He does look tired.他看上去的确累了。
(6)They did come yesterday.他们昨天确实来了。
二、与情态动词连用构成复合谓语(1)I can speak English.我会说英语。
(2)May I come in?我能进来吗？(3)Dare he swim across the river? 他敢游过这条河吗？(4)We must work, and above all we must believe in ourselves.我们必须工作，首先我们要信得过自己。
(5)Could you do something for me? 你能为我做点事吗？(6)You shall go at once.你得马上走。
(7)He might be working in the office now. 他这会儿可能正在上班。
(8)I don't think you need have come yesterday. 我觉得你昨天没必要来。
(9)They should be here by now. 他们这会儿应该到了。
(10)If you will go into the fields and turn over a few big stones, you are sure to uncover a city of ant "people".如果你愿意去田间掀开几块大石头，你肯定能发现一个“义民城”。
但与情态动词ought(to)连用时通常带to，和used(to)连用时必须带to三、在表示感觉的动词如：see, look at, watch, hear, listen to, feel, notice, observe, perceive(觉察，看见),behold（书面用语“见到”）等后用作宾语补足语的动词不定。
(1)I saw her cross the street.我看见她过了大街。
(2)He looked at the children walk up the hill. 他看着孩子们上了山。
(3)I watched the boy cross the road.我看到那男孩过了马路。
(4)I heard her play the piano.我听见她弹钢琴了。
(5)He listened to us talk.他听我们说话。
(6)I felt the floor move.我感到地板动了。
(7)I didn’t notice you enter.我没注意到你进来。
(8)He observed someone open the door.他注意到有人把门打开。
(9)I did not perceive anyone come in.我没察觉有人进来。
(10)He beheld her go out.他见她出去了。
但除notice, watch不用被动语态外，上述动词变成被动语态时，其后的动词不定式就不省to(1)She was seen to cross street.有人看见她过了马路。
(2)She was heard to play the piano.有人听见她弹钢琴。
四、使役动词make, let, have, bid, leave(=let)后作宾语补足语的动词不定式不带to(1)You may take a horse to the water, but you can't make him drink.马到河边是小事，让它喝水难上难。
(2)I'll let him do it.我会让他做这事的。
(3)Don't forget to have them come.别忘了让他们来。
(4)Bid him go home.吩咐他回家。
(5)Leave him go.让他走。
动词have通常不用于被动语态，make和bid可用于被动语态，let偶尔也可用于被动态，用作主语补足语的动词不定式通常带to，但在make和let后有时可以不带to(1)John was made to wash the truck for a week as a punishment.约翰被罚洗一个礼拜的卡车。
(2)He was made(to) laugh.他被逗笑了。
(3)The child was let(to) do it.这个孩子被迫做这事。
五、never与know连用其后作宾语补足语的动词不定式可省to，其时态多为完成时态。
(1)I never knew him act without thinking. 我从来不知道他那么莽撞。
(2)I've never known it snow in July before. 我以前从来不知道七月会下雪。
(3)I had never known her ask for pity before.我以前不知道她会乞求怜悯。
有时ever与known连用也有上述用法。
(1)Have you ever known me tell a lie?你知道我撒过谎吗？六、在find后作宾语补定语的动词不定式有时可以省to，但如动词为be，那么一般不省to，要省一起省略"to be"(1)We found the farm crops(to) do well.我们发现这个农场庄稼长势很好。
(2)I find the Chinese people to be happy and cheerful.我发现中国人很快乐。
(3)I found this to be true in all the cities. 关于这一点，我发现每个城市都是如此。
(4)We found him (to be) honest/dishonest. 我们发现他诚实（不诚实）。
七、在cannot but, cannot help but, can not choose but,had better(best),would(had) rather(sooner)…than…,would as soon…as…后的动词不定一般不带to(1)When the country calls you for help, you cannot but go.当国家需要你的时候，你别无选择。
(2)He can't help but feel sorry for her.他禁不住为她感到遗憾。
(3)He cannot choose but obey.他只有服从的份儿。
(4)I had better leave now, or I'll be late. 我最好现在就走，不然就晚了。
(5)He had best buy it now while it is still available.趁现在还有，他最好买了。
(6)I would rather go mountain-climbing than just take a walk.他宁肯去爬山也不愿散步。
(7)My aunt invited me to the movies, but I said I had rather go on a picnic with the girls. 姨妈请我看电影，可我说我想陪女生去野餐。
(8)I had sooner live on a farm than in the city.我宁肯住在农场也不愿住在城市。
(9)He would sooner resign than take part in such dishonest business deeds.他宁肯放弃也不愿参与这么虚伪的事情。
(10)I'd rather not tell you.我宁肯不告诉你。
(11)He said he'd sooner die than betray his friend. 他说死也不愿出卖朋友。
八、在but(=except),besides, than后的动词不定式一般要带to，但如果其前有作谓语的实义动词do，则不定式不带to(1)The soldier has no choice but to obey. 士兵只能服从。
(2)He did not have any choice but to obey. 他只有服从。
(3)She did nothing but clean the dishes.她只洗盘子。
(4)The children found there was nothing they could do with their money, except spend it on sweets.孩子们发现他们的钱只能买些糖果。
(5)There seemed nothing else to do but(to)send for a doctor.好像只能请大夫了。
(but前的实义动词do不作谓语，but后的不定式可带to，也可不带to)(6)He did nothing else than laugh.他只好笑了。
(7)I could hardly do less than wait.我只好等待。
九、不定式作表语时，如主语部分含有实义动词do，且句子的时态为一般现在时或一般过去时(多为is或was)，不定式可以带to也可不带to(1)What we must do now is (to) find anther person to help us.我们这会儿要做的就是再找个人帮我们。
(2)All he could do was (to) rush into the room.他所能做的就是冲进房间。
如句子的动词时态不是一般现在时或一般过去时，作表语的动词不定式一般要带to(1)She knew that all she would have to do would be to stop crying.她知道她只有停止哭泣。