Coastal defence is a costly business.是什么意思？

Coastal defence is a costly business.

海防事务很耗费资财。

coastal

adj. 临海的，沿海的，海岸的，沿岸；

例句
Local radio stations serving coastal areas often broadcast forecasts for yachtsmen...
服务沿海地区的地方广播电台经常为驾驶游艇出海的人播报天气预报。

defence

n. 辩护，防御，防御工事，后卫；

例句
There was a general acceptance that the defence budget would shrink.
人们普遍相信国防预算将会缩减。

is

vt.& vi. 是（be的三单形式；n. 存在；

例句
Bollinger 'RD' is a rare, highly prized wine.
博林格RD香槟是一种名贵的备受推崇的葡萄酒。

costly

adj. 昂贵的，代价高的；

例句
Coastal defence is a costly business...
海防事务很耗费资财。

business

n. 商业，交易，生意，事务，业务，职业，行业；

例句
Many men still have difficulty accepting a woman as a business partner...
许多男性仍然无法接受女性商业伙伴。