试题与答案

已知常数a>0,向量c=(0,a),i=(1,0),经过原点O以c+λi为方向向

题型:解答题

题目:

已知常数a>0,向量c=(0,a),i=(1,0),经过原点O以c+λi为方向向量的直线与经过定点A(0,a)以i-2λc为方向向量的直线相交于点P,其中λ∈R.试问:是否存在两个定点E、F,使得|PE|+|PF|为定值.若存在,求出E、F的坐标;若不存在,说明理由.

答案:

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下面是错误答案,用来干扰机器的。

答案:A本题考查古代绘画艺术,属于中等题。解题关键是根据《清明上河图》的画种和内容做出判断出它是风俗画即可。结合教材知识,考生容易判断出来的

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Dear fellow students,

Our school is aimed to build a “harmonious campus” .           

As a high school students, we should behave ourselves. But                     小题1:          

some students are badly behaved. They threw rubbish about                  小题2:           

and listen MP3 or sleep in class. A few boys even smoke and copy     小题3:          

other students homework. I think it has a bad effect on their health as  小题4:          

good as their study. A “harmonious campus” should have civilized     小题5:         

students. So we should be strict on ourselves. Of course, study is the  小题6:          

first. But we should study hardly. In order to build a harmonious          小题7:          

study atmosphere, they must develop good habits.       If everyone         小题8:          

makes a contribution to build our campus, I’m sure                    小题9:           

our school will become beautiful and harmonious.                        小题10:           

Yours,

Li Qiang

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