单选题 One of the workers (has) (hung) the curtains that (had) been (laying) on the floor.

【正确答案】 D
【答案解析】改为lying.Lie表示“躺,位于”时,过去式是lay,现在分词是lying.而lay也为动词“放置,搁放”的原形,如laythetable。此处为前者,故用lying.