这座城堡建筑得非常牢固。

Zhè zuò chéngbǎo jiànzhù de fēicháng láogù.

This castle is built very firmly.

基础必须牢固才能支持建筑物。

Jīchǔ bìxū láogù cáinéng zhīchí jiànzhùwù.

The foundation must be firm to support the building.

这种材料的连接非常牢固。

Zhè zhǒng cáiliào de liánjiē fēicháng láogù.

The connection of this material is very secure.