27．Can you still remember the farm we enjoyed plenty of fresh fruit half a year ago?
A．that B．when C．where D．what
26．-What happened to the ancient town?
- .
A．It destroyed in the flood B．The flood was destroying it
C．The flood was destroyed it D．It was destroyed in the flood
25．-Your grandfather is always full of .What’s the secret?
-Playing Taiji every morning.
A．taste B．energy C．relief D．credit
24．--- I am always feeling nervous before an exam.
--- ．Do believe your hard work will surely pay off.
A．Take your time B．Take a good rest
C．Take it easy D．Take your turn
23．Although you have traveled to many scenic spots before, of them are as attractive as the one I visited this summer vacation.
A．any B．none C．neither D．all
22．--- I am sorry to have much of your spare time.
--- That’s OK, and I am glad to help you.
A．taken up B．taken on C．taken off D．taken in
第一节：单项填空(共15小题，每小题1分，满分15分)
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
21． moment he saw Zhao Benshan’s funny performances, he burs into laughter.
A．A;不填 B．A；the C．The;不填 D．The; a
12．(16分)设数列{an}的前n项和为Sn，
已知a1＝1,2Sn＝(n+1)an(n∈N*)．
(1)求a2，a3，a4的值；
(2)写出从an－1到an的递推公式；
(3)求数列{an}的通项公式．
[解析] (1)由2(1+a2)＝3a2，得a2＝2.
由2(1+2+a3)＝4a3，得a3＝3.
由2(1+2+3+a4)＝5a4，得a4＝4.
(2)∵2Sn＝(n+1)an(n∈N*)，
∴2Sn－1＝nan－1(n>1)，
两式相减，得2an＝(n+1)an－nan－1，
∴递推公式为an＝an－1(n>1)．
(3)由(2)得an＝an－1
＝·an－2
＝··an－3
……
＝···…··a1＝na1.
又∵a1＝1，
∴数列{an}的通项公式为an＝n(n∈N*)．