She watched him go with a sinking heart.

她心情沉重地看着他走了。

《牛津词典》

With a sinking heart, I realized that I was on a deserted island.

带著一颗深沈的心，我明白自己是在个荒芜的岛上。

youdao

I would like to work in a high sense of responsibility and sense of honor is the dedication sinking heart.

我想，工作中高度的责任感和荣誉感才是那颗爱岗敬业之心。

youdao

And I could feel my heart sinking into my stomach.

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