Life is not a sad tone, if you are optimistic enough.

生活的色调不是悲伤，如果你是足够乐观的。

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The message has an emotional tone that is authentically sad/fearful/angry and at the same time, is by marked by a rueful calm, by gentleness, and by courage.

这里边有一种真正悲哀/恐惧/愤怒的情绪化腔调，与此同时又带有悔恨的平静、温顺和勇气。

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Only a solitary cracked-voiced reed-sparrow greeted her from the bushes by the river, in a sad, machine-made tone, resembling that of a past friend whose friendship she had outworn.

只有一只声音嘶哑的芦雀，在河边的树丛中用悲伤机械的音调向她打招呼，就像一个已经没有了友谊的从前的朋友向她打招呼的声音一样。

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How else to explain the sad-sack tone from the leaders of the four biggest U.S. banking companies after their respective earnings announcements in the last week?

WSJ: Debbie Downers on Wall Street

"Coming here makes me sad, " Bush said in a hushed tone as he spoke to service members and emergency workers gathered on the grounds.

CNN: No hope of finding more survivors at Pentagon