地下街

• 土(earth; soil; land)RADICAL
• 也(also; punctuation mark (archaic))PHONETIC

The wide earth (soil) is also where all things flourish and grow.

• 一(horizontal line; boundary)RADICAL
• 卜(stroke descending downward)ASSOCIATIVE

A vertical stroke pointing downward across a boundary line marks 'below'.

• 行(path; step)RADICAL
• 圭(jade; precious stone)PHONETIC

A street is the road where people walk, with sound borrowed from the pointed tool.