已知定义在R上的函数f（x）=2^x﹣$\frac{1}{2^x}$．

（1）若f（x）=$\frac{3}{2}$，求x的值；

（2）若2^tf（2t）+mf（t）≥0对于t∈1，2恒成立，求实数m的取值范围．

人类和类人猿的共同祖先是                                   （    ）

关于电流，下列说法正确的是（　　）

    Hello! I'm Sally. I'm an English girl. Now I'm in Beijing with1parents. Today is Sunday. I2to Yangguang Clothes Store. Wow! I see lots of3clothes in it. They have sweaters at a good4. They have some bags5sports. They have hats in red, black6yellow. The white7are on sale. They8only 15 dollars. I think they are cheap(便宜的), so I9a small one for myself and a large one for my10.