170.Fred used tolate with his roommates to play computer games.

30.One of the requirements for combustion（燃烧）is that the materialto its burning temperature.

29.It＇ s high timeabout the traffic problem now.

28., everything would have been all right.

27.It is necessary that hethe task by the end of next week.

26.next week, he would be able to see the opening ceremony.

25.I don＇t think it advisable that Tom to the job since he has no experience.

24.tomorrow, she would get there on Sunday.

23.1 am sorry that he in such poor health.

22.He asks that hean opportunity to explain why he refused to go there.

21.You didn＇ t take his advice. his advice, yousuch a mistake.