They spend two hours on their work.保持句意不变 They spend two hours ___英语解答

They spend two hours on their work.保持句意不变 They spend two hours ____their work.

人气：358 ℃　时间：2019-08-20 18:18:36

解答

spend 时间 on sth.花时间在某事上 =
spend 时间 in doing sth.花时间做某事 ,这个结构里in可以省略
所以一个空格填写:finishing