题目内容：

The new pair of trousers _____ so little that I will buy two pairs
A.are B.is C.costs D.seem

优质解答

选C.
The new pair of trousers是单数,a pair of 是一条的意思,所以是单数,用costs.
costs so little是价钱低的意思,符合句意
整句意思是：这条新的裤子太便宜了,我要买两条!