must,should,ought三个词的区别与用法源于must have dropped itshould have droped it ought to have dropped it难得深夜还有人在，还能帮我解决疑问
问题描述：
must,should,ought三个词的区别与用法
源于
must have dropped it
should have droped it
ought to have dropped it
难得深夜还有人在，还能帮我解决疑问
答
must 强调的是客观上的要求，而should 强调的是主观上的意愿。
ought to 则是一般的用法。
答
1.一定已经......
2.应该已经......
3.应该已经......
(should和ought to都是“应该”之意,但后者要比前者语气要强得多 ).