a.

1. 经济的，节约的
   This car is economical to run because it doesn't use much fuel.

   开这辆车省钱，因为它耗油不多。

   be economical of time and energy

   节省时间和精力

   It's not an economical method of heating.

   这不是一种经济的取暖方式。

2. 节俭的
   She is an economical housewife.

   她是个节俭的家庭主妇。

3. 经济学的；经济上的

adj.