题目

()10的展开式中含x的正整数指数幂的项数是(    )A.0              B.2                 C.4             D.6 答案：答案:B解析:通项Tr+1=试根易得B.The old lady doesn’t have any children. She lives _________ in a _________ house. A．alone; alone       B．lonely; lonely       C．alone; lonely       D．lonely; alone