I am too sad to go on with my work.

我太伤心了，以至于我不能继续我的工作。

youdao

It was sad to see them go.

看着他们离去，真让人难过。

《牛津词典》

I was sad that she had to go.

知道她得走了，我心里很难过。

《牛津词典》

And so, when we took a field trip to go see the SF Chronicle, it was really, really sad.

我们去《旧金山纪事报》的报社看过，发现他们真的很萧条。

旧金山的报纸 - SpeakingMax英语口语达人

"I am sad to go but I'm looking forward to the new challenge I'll face at Newcastle, " said Hogg.

BBC: Allister Hogg switch excites Falcons coach Alan Tait

We know Reader has a devoted following who will be very sad to see it go.

FORBES: Google Reader Is Dead, Long Live Google Reader

Nevertheless, I will be sad to see Taymor go, if the reports are true.

FORBES: Julie Taymor Reportedly Leaves Spider-Man