随着城市的快速发展，地铁线路不断向郊区延伸。

Suízhe chéngshì de kuàisù fāzhǎn, dìtiě xiànlù bùduàn xiàng jiāoqū yánshēn.

As the city develops rapidly, the subway lines keep extending toward the suburbs.

这个概念可以延伸到其他学科来讨论。

Zhè gè gàiniàn kěyǐ yánshēn dào qítā xuékē lái tǎolùn.

This concept can be extended to other disciplines for discussion.

这条河从山里延伸到海边。

Zhè tiáo hé cóng shānlǐ yánshēn dào hǎibiān.

This river extends from the mountains to the seaside.