题目

Big Brother“What! I’m a boy. I can’t look after a baby!” I said to Mom. But she wasn’t listening.“Don’t be difficult, it’s only for an afternoon. I will help your Aunt Judy with her birthday party.”Mother said as she got ready to go out. Then the door closed and I was left alone with my ______. So unfair (不公平), I thought. I should be out playing football with my classmates. I was quite ______ being the only child for thirteen years. Why did my parents have another kid?When I was watching TV in the sitting room, I heard the cry of my sister. I remembered what Mother said函数y=2x+3x+1的图象的对称中心是：______．