在做此类题时,通常在系动词、助动词和情态动词后加not (n't)。如果句中没有这些词,则根据谓语动词的原形、第三人称单数动词形式或过去式而分别在其前面加do not (don't), does not (doesn't) 或did not (didn't), 并将第三人称单数动词形式或过去式改为原形。如:
We can finish the work this afternoon. →We
can't finish the work this afternoon.
They put the basket under the tree just
now. →They didn't put the basket under the tree just now.
注意:1. 当think, believe, suppose等动词后面跟宾语从句时,通常用否定主句谓语动词来达到否定从句谓语动词的目的。如:
I think they can come tonight. →I don't
think they can come tonight.
2. 当must表示推测,表示“一定;肯定”的含义时,否定句应用can't。如:
He must be in the room. →He can't be in the
room.