这个物体的体积是____立方厘米
若函数y=f(x)在R上可导且满足不等式xf′(x)+f(x)>0恒成立,且常数a,b满足a>b,则下列不等式一定成立的是( )
请画出下面物体所受到的重力和支持力的示意图.
—How many people were invited to the meeting?
—About six ________.