Correct

井下

/ jǐngxià / 
Strokes

Definition

underground/in the pit (mining)

Example

As a Noun

(in) the pit; (under) the shaft

1
Jǐng
井
xià
下
zuòyè
作业

under- pit operation

2
Jǐng
井
xià
下
cǎiméi
采煤
ōu
区

underground coal mining district

3
Jǐng
井
xià
下
bàozhà
爆炸

well blast