It was sad to see them go.
看著他們離去，真讓人難過。
You'd have to be sad to wear a shirt like that.
你穿著那樣的.襯衣顯得老氣。
I was very sad indeed to hear of your father's death.
聽到令尊大人去世，我感到非常難過。
We are very sad to hear that you are leaving.
聽說你要走了，我們十分難過。
Her moods kept changing ─ now happy, now sad.
她的情緒總是變幻不定——時而歡喜，時而憂傷。