Q表示产量,成本C(Q)=100+13Q，单价p，需求量Q(p)=800/P+3-2则工厂取得利润最大时的产量为_____

求曲线y=x^2与直线y=0，x=1所围成的平面图形绕x轴旋转一周所得旋转体的体积V.

Thewealthofacountryshouldbemeasured________thehealthandhappinessofitspeopleaswellasthematerialgoodsitcanproduce.

You________gonow.It’sgettinglate.

Hefellasleepimmediatelylastnight;hemust________(be)verytired.