Definition: not using a lot of money, fuel, etc. Level: B2
给这栋楼供暖最经济的方式是什么？
What's the most ___economical way of heating this building?
对更省油的汽车需求日益增长。
There's increasing demand for cars that are more ___economical on fuel.
而且，自行车是一种非常经济的交通工具，因为它不需要任何燃料。
Moreover, a bike is a very ___economical means of transport because it does not need any fuel.
