have 与Have got

在表示一次性动作时,have to和have got to是可以互换的,如：I have (got) to be back by ten o'clock。我必须10点前返回来。I haven't got to work tomorrow。我明天不必上班。但是,当表示习惯性动作时,尤其是当句中含有表示经常性的副词 （如always,often,sometimes等）时,则应使用have to,而不使用have got to,如:I don't usually have to work on Sundays。通常我在星期天不必工作。I often have to get up at 5。我常常不得不5点钟起床。看下面两个句子：Jim's got to check the temperature every 12 hours。Jim has to check the temperature every 12 hours。have got to 一般没有“习惯性”的含义,而且,当它和具有动态意义的动词连用时,常常是指将来……。第1句可能含有指示,命令的意思,规定吉姆将来的职责；而第2句更加可能是表示一种习惯性动作（这就是吉姆现在的职责了）。have to 与 have got to的另一区别,就是后者不大用于过去时,如：They didn't have to worry about money。他们那时不必为金钱而操心。I had to walk very fast to catch up with you。为了赶上你,我不得不走得很快。最后一个区别,就是have to 前可加助动词或情态动词,或者用在进行时和完成时结构中,而have got to却不能,如：I shall have to help him as much as I can。我不得不尽我所能去帮助他。He may have to cancel his plan。他也许不得不取消他的计划。People are having to boil their drinking water during this emergency。在这个紧急状况下,人们必须煮沸他们的饮用水。The administration has had to make unpopular decisions。行政部门不得不做出不得人心的决定。