$\overrightarrow{e_1}$、$\overrightarrow{e_2}$是不共线的向量，$\overrightarrow{a}$=$\overrightarrow{e_1}$+k$\overrightarrow{e_2}$，$\overrightarrow{b}$=k$\overrightarrow{e_1}$+$\overrightarrow{e_2}$，则$\overrightarrow{a}$与$\overrightarrow{b}$共线的充要条件是实数k等于（　　）

发生在美国的金融危机会形成一条连贯的路径，将危机传导到他国。这条路径是（   ）
①消费下降，消费资料进口减少             ②失业增加，居民收入减少
③生产下降，生产资料进口减少             ④融资困难，企业倒闭增多

2010年10月28日，十一届全国人大常委会第十七次会议通过的《中华人民共和国社会保险法》规定，基本养老保险基金逐步实行全国统筹，其他社会保险基金逐步实行省级统筹，具体时间、步骤由国务院规定。这表明( )

不能判定两个直角三角形全等的条件是（　　）

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    Hi. I am Maya. I am 13 years old. I am from Africa. My father is a teacher and my mother works in a hospital. Now they are working in Beijing. They both like their work and work very hard. My father's favorite animal is the panda, but I like dolphins best.
    I am studying in a middle school. And I like music and drawing best. I want to be a designer. I like to design my room. I like the color pink, so there are a lot of pink things in my room.
    I have three friends in my room. They are Mike, Dora and Peter. They are my toys. I love them. Every night, they sleep with me.