The stock of money and its rate of expansion are not variables that the monetary authorities can control at will . 货币存量及其增长率不是货币当局能随意调节的变量。
In economic optimization problems the variables involved are almost always subject to certain constrains . 在经济学最优化问题中所含的变量差不多总是带有某种约束条件。
It needs to be able to provide good estimates of economic variables with incomplete information . 需要在信息并不完备的情况下，能够提供一些经济变量未来值的较好的估计。
Since scalars are independent of the coordinate system, the dot product of two vectors is called a scalar invariant . 因为标量与坐标系无关，故两个矢量的点积称为标量不变量。
If the shear strength variable had a value of 0. 15, however, the dead regions would be large and the plug would be large . 假如该剪切强度变量为015，则停滞区和颈区都要变大。
Only a few birth order affects were both sensible and reliable, and those seemed to be mediated by other variables . 只有少数胎次影响是合理的和可靠的，而这些影响看来还受其他变量的影响。
