回答

・it's a bothersome
・it's a source of concern

「煩惱的原因」英語是 it's a bothersome 或 it's a source of concern 來表達。

My bothersome is that my listening skills are weak.
（我的煩惱的原因是我的聽力能力很弱。）

I have confidence in my technique, but my lack of stamina is a source of concern.
（我對自己的技術很有信心，但缺乏耐力是個問題。）

ˇ以上提供你參考。

有幫助｜0