HSK 5 HSK V4
Correct

公元

/ gōngyuán / 
Strokes

Definition

CE (Common Era)/Christian Era/AD (Anno Domini)

Example

As a Noun

Christian era

1
Gōngyuán
公元
1999
1999
nián
年

1999 AD

2
Gōngyuán
公元
21
21
shìjì
世纪

21st century AD