题目

 ----Where is Jack?  ----On the playground. He _______ football with his classmates. A. play   B. played   C. is playing   D. was playing 答案：C下列除哪项外，都是生命特征的表现（ ）A．蜻蜓点水B．种子萌发C．森林着火D．人的呼吸