Shenzhen has several crossings leading into Hong Kong.
Tips
usage
An officially designated crossing point where customs and immigration operate, whether by sea, land or air. A working harbour without that status is a 港口, and the checkpoint you physically queue at is the 关口.
mistakes
The pinyin takes an apostrophe, kǒu'àn, because the second syllable begins with a vowel and the mark shows where the break falls. It is the same rule that gives 西安 and 天安门. Dropping it is the usual slip.
