士兵们在边境修建了坚固的防御工事来抵挡敌人的进攻。

The soldiers built strong ___fortifications along the border to defend against enemy attacks.

古代城堡的防御工事是为了抵御敌人的进攻而建造的。

The ancient castle's ___fortifications were built to defend against enemy attacks.

良好的教育是抵御贫困的有力堡垒。

A good education serves as strong ___fortifications against poverty.