■should与ought to的比较
(1) 除表示“万一”“竟然”等只能用should外,表示“应该,应当”“可能”等,两者可互换,只是ought to的语气稍重.如：
You ought to/should work harder than that.你应当更努力地工作
She ought to/should finish it by next week.下星期她可能完成了.
You ought to/should have told him about it earlier.你本应该早点把这件事告诉他的.
You oughtn’t to/shouldn’t have wasted time like that.你本不该像那样浪费时间的.
(2) should 强调主观看法,而 ought to 强调客观要求.如：
We ought to go and see my mother in hospital tomorrow,but I don’t think we will.我们按理应当在明天去看看住院的母亲的,但我主认为我们不会去.
(3) 在公告、须知或条例中,出于礼貌,常用should.如：
You shouldn’t run alongside the swimming pool.不准在游泳池边奔跑.
(4) 在虚拟语气中只能用should.如(from www.***.com)：
He suggested that I should go there.他建议我去那里.
(5) 注意ought to的否定式与疑问式.如：
You ought not to do it.你不应该做此事.
—Ought he to start now?他现在该动身了吗?
—Yes,he ought (to) .是的,该动身了.
They ought to go now,oughtn’t they?他们现在该走了,对吗?