2 sentences

1. 此地形势险要，是一个军事要塞。

   cǐ​dì xíng​shì xiǎn​yào, shì yī gè jūn​shì yào​sài.

   The terrain here is strategically critical; it is a military fortress.

   Source: Dong Chinese Dictionary

2. 此处地势险要，是连接两省的咽喉要道。

   cǐ​chù dì​shì xiǎn​yào, shì lián​jiē liǎng shěng de yān hóu yào​dào.

   The terrain here is strategic, serving as a vital passage connecting the two provinces.

   Source: Dong Chinese Dictionary