牢固

牢固

Secure; firm; solid.

In this sentence, '牢固' is used as an adjective to describe the bridge's structure as sturdy and solid.

这座桥的结构非常牢固，能够承受极大的压力。

The structure of this bridge is very sturdy and can bear a great amount of pressure.

Here, '牢固' describes the cabinet's connections, emphasizing their improved stability.

经过多年的维修，这个柜子的连接变得更加牢固。

After years of maintenance, the cabinet's joints became more secure.

Here, '牢固' metaphorically describes the foundation of friendship as solid or reliable.

人与人之间的友谊需要牢固的基础才能经得起时间的考验。

Friendship between people requires a solid foundation to stand the test of time.