乙炔胶管管段的连接，应使用含铜（）以下的铜管、低合金管或不锈钢。
A．70％
B．90％
C．80％
参考答案：A
能引起人、猪等患“甲型H1N1流感”的病原体属于以下哪种病毒类型（ ）
A．细菌病毒
B．植物病毒
C．噬菌体
D．动物病毒
—May I come in?
—Come in, please. But could you please tell me ____? [ ]
A. why you're late again
B. what were you doing then
C. who you talked
D. how do you come to school
