将下面常见食物根据富含的营养素分类．
蛋；水果；牛肉；土豆；玉米；蔬菜；鱼；小麦；红薯；奶；大米
可以用图象来表示物体的运动状态，如图所示，表示物体运动速度相同的是（ ）
最早使用负数的国家是（ ）
—Too much homework has made me tired these days, Mr. Wang.
—That's true. But a small tree won't grow into a big tree it experiences lots of winds and rains.
