costly的基本含意是“昂贵的”,不在于价钱上贵而在于其豪华、精致、珍贵。costly还可用于时间、精力和体力。

用作定语
▲～+n.
We need some costly materials.我们需要某些价值昂贵的材料。
This is the costliest war in our history.这是我们历史上付出代价最大的战争。
用作表语
▲S+be+～
The victory is costly.这一胜利的代价很高。
▲S+be+～(for sb)+to-v
The house is too costly for us to buy.这房子太贵了,我们买不起。

costly, dear, expensive
参见dear条。

［同义词］   dear, expensive, high, valuable
［反义词］   cheap, inexpensive, low-cost