洞口 + Location Phrase
The noun 洞口 (dòngkǒu) means "cave entrance" or "opening of a cave." It combines 洞 (cave) and 口 (mouth/opening) to specifically refer to the point of entry or exit of a cave. It is commonly used in narrative and descriptive writing.
一股冷风从洞口吹了出来。
yī gǔ lěngfēng cóng dòngkǒu chuī le chūlái.
A gust of cold wind blew out from the cave entrance.
他们在洞口生了一堆火来取暖。
tāmen zài dòngkǒu shēng le yī duī huǒ lái qǔnuǎn.
They lit a fire at the cave entrance to keep warm.
洞口太小了,只能一个人侧身通过。
dòngkǒu tài xiǎo le, zhǐ néng yī gè rén cèshēn tōngguò.
The cave entrance is too small; only one person can squeeze through sideways.