HSK 4 · noun · Practice
原因
cause; reason; root cause
他迟到的原因是堵车。
Tā chídào de yuányīn shì dǔchē.
The reason he was late is the traffic jam.
我们只能猜测他迟到的原因，谁也不确定。
Wǒmen zhǐ néng cāicè tā chídào de yuányīn, shéi yě bù quèdìng.
We can only guess why he was late; nobody is sure.
经常锻炼身体，是长寿的重要原因。
Jīngcháng duànliàn shēntǐ, shì chángshòu de zhòngyào yuányīn.
Exercising regularly is an important reason for a long life.
他的努力无疑是成功的原因。
Tā de nǔlì wúyí shì chénggōng de yuányīn。
His hard work is undoubtedly the reason for his success.