21.One of the mosteffective ways to reduceisto talk tosomeone you trust.

39.a strange plant! 1 have never seen it before.

38.at the door before you enter the room, please.

37.a wonderful trip he had when he traveled in China!

36.It was because it rained heavily yesterdayhe could not come to the evening school on time.

35.It is during his spare timeDavid has been working on making his motorbike.

34., he is one of those who have made the most important contributions to the organization.

33.There wasn＇t anyone in the room at that time, ?

32.Go and get some water, ?

31.He used to get upatsixin the morning, ?

30.You never told us his phone number, ?