ComradeLi________beinBeijingbecauseIsawhimintownonlyafewminutesago.

Thewealthofacountryshouldbemeasured________thehealthandhappinessofitspeopleaswellasthematerialgoodsitcanproduce.

曲线在点（0，-1）处的切线方程为________.

I'msorryIforgottowrite;Ihadsomuchelse________mymind.

设曲线L:f(x,y)=1(f(x,y)具有一阶连续偏导数)，过第II象限内的点M和第IV象限内的点N，T为L上从点M到点N的一段弧，则下列小于零的是（）