This is the 2148th most frequent Chinese word.
延伸
"Extend" or "stretch out."
In this sentence, '延伸' (extend) is used to describe the action of the railway continuing in length or scope.
这条新建的铁路将一直延伸到山区深处。
This newly constructed railway will extend deep into the mountainous area.
Here, '延伸' (extend) is applied in a figurative sense, indicating the broadening or deepening of knowledge or perception.
阅读这本书让我对历史的认识得到了延伸。
Reading this book has extended my understanding of history.
In this context, '延伸' (extend) is used to discuss the physical expansion of infrastructure in a city.