牢固

In a sentence

• 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.

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

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

• 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.

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