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问题 选择题
直线l1：ax+by+c=0，直线l2：mx+ny+d=0，则
am
bn
=-1是直线l1⊥l2的（　　）
A．充要条件B．既不充分也不必要条件
C．必要条件D．充分不必要条件
答案

直线l1⊥l2的，所以am+bn=0，推不出

am
bn
=-1；

但是

am
bn
=-1可以得到am+bn=0，两条直线垂直，

所以直线l1：ax+by+c=0，直线l2：mx+ny+d=0，则

am
bn
=-1是直线l1⊥l2的充分不必要条件．

故选D．

听力题

(a) Nobody before Jane fully understood chimp_____1_____. She spent years _____2______ and recording their daily activities. Since her ______3_______ she had wanted to work with animals in their own environment.

(b) For forty years Jane Good all has been ______4_____ about making the rest of the world understand and ____5______ the life of these animals. She has ____6_____ that wild animals should be left in the wild and not used for ______7_______ or advertisements.

(c) Indeed, his ____8____ face and arms and his slim, strong body are just like those of millions of Chinese farmers, for___9____he has____10____for the past five ____11______ .

(d) Dr Yuan is quite _____12_____ with his life. However, he doesn’t ____13____ about being famous. He feels it gives him less ____14______ to do his research. He would much ___15_____ keep time for his hobbies
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单项选择题

个体工商户抵押贷款和质押贷款的期限在一年（含）以内的，采用按月（季）付息（）的还款方式；贷款期限在一年以上的，原则上采用按月（季）付息（）的还款方式。

A.任意还本，分期还本

B.分期还本，任意还本

C.一次还本，分期还本

D.分期还本，一次还本
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