五、词汇（共15小题，每小题1分，满分15分）

A) 根据汉语提示及句意，写出所缺单词，使句子意思完整正确。

51. Simon is helpful, he often ____________(提供) me help .

52. Susan is an __        ______(极好的) friend. We all like her.

53. No one knows 　　　              (确切地) when Chinese first grew watermelons.

54. Tom is one of the best ______________(游泳者)in our class. 

55. You should look                            （自始至终）the instructions first.

B) 用括号中所给词的适当形式填空，使句子意思完整正确。

56. I’m sure he can finish the work in time by                   . (he)

57. We are 　　　     　 (certain) what will happen. Let’s wait and see.

58. Your diet seems to work very well. You look much 　　         　(slim) now.

59. The teacher made the students ____________(discuss) with each other in class.

60. The ticket is _____________(use) now, however, I’ll keep it.