题目

根据短文内容，选择正确答案。CDear Ms. Li, I'm very glad to write to you. I'm a junior student. I have a lot of troubles these days. Every day I have a lot of homework to do at school. I don't have enough time to sleep. I nearly have no time to do sports. My friends and I can hardly find time to talk or play together. When I get back home from school, I have to do my homework. I'm not allowed (不被允许) to watch TV, surf the Internet or listen to my favorite music. I feel worried. I miss those old days when I was in primary school. At that time, I had a lot of time to have fun18．已知C${\;}_{2013}^{1006}$+C${\;}_{2013}^{1007}$=C${\;}_{n}^{\frac{n}{2}}$，（2x-3）n=a0+a1（x-1）+a2（x-1）2+…+an（x-1）n，x∈R，n∈N*，则$\frac{{a}_{1}}{2}$+$\frac{{a}_{2}}{{2}^{2}}$+…+$\frac{{a}_{n}}{{2}^{n}}$的值为（　　）A．-1B．0C．1D．2