20. He was reading a book at this time yesterday.

21. They must finish the work today.

22. We should listen to the teacher carefully in class.

23.The boss made the workers work 14 hours a day.

24.I often hear  him sing in his room.

25.Tom helped an old man walk across the street yesterday.

26.He showed the photos to Lily. = He showed Lily the photos.

             直接宾语    间接宾语

27.Grandma often tells  me    stories. = Grandma often tells stories to me.liuxuepaper.com