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问题 选择题
若双曲线
y2
4
-
x2
5
=1的焦点为F1，F2，P是双曲线上的一个点，则||PF1|-|PF2||的值为（　　）
A．9B．2C．3D．4
答案

由题意可得 a=3，根据双曲线的定义得出||PF1|-|PF2||=2a

则||PF1|-|PF2||的值为4．

故选D．

写作题
假设你是某中学高三(1)班学生李华。下面是你校布告栏里张贴的“征集接待家庭”的通知，请根据其内容用英语写一封申请信。词数不少于100。
注意：信的开头和结尾已经给出（不计入词数）。
HOST FAMILIES WANTED
Some foreign teachers and students from an American high school will study in our school during the summer vacation. Host families are wanted to accommodate our friends.
REQUIREMENTS:
◇ Good English.
◇ A SEPARATE room.
◇ transportation.
◇ …
If interested, please send your APPLICATION IN ENGLISH to the International Department before SATURDAY. Please consult us for any further information.
 
Dear Sir/ Madam,
I am Li Hua from Class One, Senior Three.                                     
                                                                              
                                                                              
                                                                              
Yours sincerely,
Li Hua
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单项选择题

按项目的( )可将项目划分为政府投资项目和非政府投资项目。

A．投资来源

B．经济效益

C．投资规模

D．市场需求
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