Old people often try to economize on heating, thus endangering their health.

老年人常常想方设法节约用暖气，结果损害了他们的健康。

We must economize on fuel.

我们必须节约燃料。

We must economize on water.

我们必须节约用水。

The power enterprises shall economize on water.

电力企业应当节约用水。

We should economize on all kinds of energy.

我们应该节约各种能源。