be economical of one's money

For ensuring the mining production to be economical, continuous and in a state of equilibrium, one of the necessary steps to be taken is to account, determine, and balance the workable ore reserves.

各级矿量的计算与确定以及其间的平衡是保证矿山经济合理地持续、均衡生产的必要条件之一。

The closed loop circulation, one of the most economical and effective treating methods, should be developed.

闭路循环是最经济最有效的处理方法之一，应予以推广。

Moreover, the bandwidth is a very limited and precious resource. And the low code rate speech codes is one of the important methods to be economical bandwidth.

信道带宽是非常有限和宝贵的资源，而低码率语音编码技术是节省带宽的重要方法之一。