他们在海边修建防波堤来加固海岸线。

They are ___fortifying the coastline by building breakwaters along the shore.

锻炼可以增强你的身心力量。

Exercise is great for ___fortifying your body and mind.

这种牛奶被强化了维生素D，有助于骨骼健康。

This milk is ___fortified with vitamin D to support bone health.