39. We can't exist without water.　 存在　　　 come into existence = come into being

38. I am exhausted. = I am tired out. = I am worn out.　

37. excuse sb from 免除…的责任, 对其要求　 He was excused from piano practice.

36. Please excuse my interrupting you.= Please excuse me for my interrupting you.

35. make an excursion to sp 到…短途旅行　　　　　　 an excursion train 旅游专列

34. exchange our opinions 　交换　　　　　 exchange A for B 用A换B

in exchange for 作为…的交换　　 I gave him my favorite football in exchange for his knife.

33. speak evil of sb 讲…坏话　　 speak highly of sb

32. at all events , in any event (in any case)　 无论如何，在任何情况下　　

In any event, the worst that she can do is say “no”　　

31. it is estimated that…　 estimate the cost 估价　　　 the estimated cost 估计的成本

30. Water is essential to the growth of crops.　 必要的　

There is no essential difference between them. 本质上的