ought to意思是“应该”,是情态动词,只有一种形式,后边接动词不定式,to不能省略。ought to没有人称和数的变化,后接动词原形可以表示现在、将来或过去将来,由时间状语或上下文决定。 They ought to come tomorrow. He thought that they ought to take part in the design.
ought to