Correct

天黑

/ tiānhēi / 
Strokes

Definition

to get dark/dusk

Example

As a Noun

deepening dusk; dark

1
Nǐ
你
yīdìng
一定
yào
要
zài
在
tiānhēi
天黑
qián
前
huílai
回来
  
。

You must be back before dark.