Hello, I'm Sam. I'm from England. Now I am in Beijing with my family.  I've got a pet dog.  It's lovely and nice.

    Tomorrow is Sunday. My sister Amy is going to have a birthday party. Now I'm making a card for her. Dad is buying things at the supermarket. Mum is making a cake for her. What can my pet dog do for Amy? Oh, it can sing and dance for her!

已知点P在曲线$y=\frac{4}{e^x+1}$上，$\alpha$为曲线在点P处的切线的倾斜角，则$\alpha$的取值范围为（   ）

如果把分式 中的x和y都扩大10倍，则分式的值（　　）.