题目

在代数式： 中,单项式有               （      ） A、3个        B、4个           C、5个           D、6个 答案：C Hurry up, Jack．We have to get to the station before 11∶45 ________ we can catch the 12∶00 train． [　　] A．since B．after C．as soon as D．so that