题目

 —I’d like to spend my weekend in the countryside, but my car has broken down.    —______________.You can take mine.    A. What if .      B. Take your time.     C.What a pity.        D. It’s no big deal. 答案：D生物种类最少的生态系统是（　　） A、草原生态系统B、农田生态系统C、森林生态系统D、海洋生态系统