26.The visitors _______ (arrive) at the factory an hour ago.

25._______ Li Ping with his family _______ (watch) TV now?

24.I _____ never _____ (read) the book.

23.He _____ just _____ (buy) the dictionary.

22.We ______ (hear) of the name of the computer before.

21.Have you ever _____ (visit) the science Museum?

20.- How long _____ it _____ (take) you to clean the classroom yesterday ?

　 - If _____ (take) is twenty minutes.

19.They _______ (laugh) when the teacher came in.

18.I think it ______ (be) cloudy tomorrow.

17.She usually ______ (come) to school on foot, but we usually _____ (come) to school by bike.