Correct
三九
/ sān jiǔ /
Strokes
Example
As a Noun
third nine-day period after the winter solstice—coldest days of winter; depth of winter
1
Xià
夏
liàn
练
sānfú
三伏
,
dōngliànsānjiǔ
冬练三九
intensify your exercise in the hottest days of summer and in the coldest days of winter—practice in the hardest condition yields the best results
2
Sānjiǔ
三九
tiānqì
天气
bitterly/extremely cold weather