DME系统采用（）
A.水平极化波
B.垂直极化波
C.椭圆极化波
D.右旋圆极化波
参考答案：B
I fell in love with the West Lake ____ I went to Hangzhou.
A．for the first time
B．first time
C．the first time
D．for first time
急性腹泻的病程为___________，迁延性腹泻的病程为___________。
