题目

 I was really anxious about you. You _____ home without a word. A. mustn’t leave   B. shouldn’t have left  C. couldn’t have left  D. needn’t leave 答案：B在脊椎动物中，以下哪项不属于哺乳动物（　　）A．海马B．海豹C．熊猫D．白鳍豚