高效液相色谱分析所用的检测器按适用性可分为（）检测器和通用型检测器。
参考答案：选择性
--- Dad, I ______ the theatre for a while, but I left my ticket at home.
--- Don’t worry, my boy, I will take it to you.
A．have reached
B．will arrive at
C．have been at
D．get to
多项式2x3-x2y2+y3+25的次数是（ ）
A．二次
B．三次
C．四次
D．五次
