题目

完形填空阅读下面的短文，从短文后各题所给的A、B、C、D四个选项中，选出一个可以填入空白处的最佳选项。Parents who have teenage children sometimes find   1   difficult to communicate with them. Learning to read teen body language is one way to get an idea of what they are trying to tell you. Communication skills, just  2    any other skills, must be learned. If you study and watch your teens’ carious body language, you will     3     communicate with them in a more effective way.★ Read teen body language by looking at the   4   .定义运算，比如2?3=，下面给出了关于这种运算的几个结论：①2?（﹣3）=；②此运算中的字母均不能取零；③a?b=b?a；④a?（b+c）=a?c+b?c，其中正确是（　　）A. ①②④ B. ①②③ C. ②③④ D. ①③④