单项选择题
The underlined word "alternate" in this passage means （）
A．keep up B．take up C．arrange by turns D．cause to take place
单项选择题 According to this passage, which of the following is right（）
单项选择题 Middle-aged people may feel subhealthy, because （）
单项选择题 before he arrived at the farmer's house, the writer expected to see Milly lying （）
