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问题 选择题
{an}是等差数列，a1=15，S5=55，则过点P（a2，4），Q（a4，3）的直线的斜率为（　　）
A．4B．
1
4
C．-4D．-
1
4
答案

∵{an}是等差数列，a1=15，S5=55=5a3，

∴a3=11，设{an}的公差为d，

则a4-a2=a3-a1=2d=11-15=-4，

∴过点P（a2，4），Q（a4，3）的直线的斜率k=

3-4
a4-a2
=
-1
-4
=
1
4
．

故选B．

完形填空

情景交际运用

IX. 根据短文内容，选择填入恰当的词语。（每空一词，每词1分，共6分）

Linda and Jenny are senior 3 students in our school. They are from Hong Kong. It is a busy city, and sometimes it is very 小题1: n______ because of so many tourists. Different from that, Xiamen is more 小题2:p           . Linda is a quiet girl so she likes to study here very much. But her sister Jenny 小题3: p        Hong Kong because she loves shopping.

After 小题4: g             next year, Linda will go to London for further education, and Jenny is going back to Hong Kong. Linda learns from a travel book that the 小题5:w_________ there is rainy. She needs to prepare an umbrella and a raincoat. Jenny thinks that she will be really小题6:c___________ when she comes back to Hong Kong.

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单项选择题

下列园林树木中，较难移栽的是（）。

A.国槐

B.毛白杨

C.垂柳

D.云杉
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