We should learn to smile, never let the blue mood around you and your face.

我们应该学会微笑，不要让忧郁的心情环绕你及写满了忧伤的表情。

youdao

In sharp contrast to her mood, the clouds were breaking up to reveal a blue sky.

乌云渐渐散开，露出了蓝天，这和她的情绪形成了鲜明的对照。

《牛津词典》

Combining red, green and blue LEDs to produce white light has the potential to be more efficient, and the colour of the light could be tuned depending on mood or taste.

结合红绿蓝led一起生成白光有能被更有效利用的潜在可能，并且光的颜色还可以依据心情或者口味来调配。

youdao

Duke Ellington and his orchestra recorded a famous song Mood Indigo about the deep blue color,indigo.

VOA: special.2009.11.15

In the words of the song: "You ain't been blue till you've had that Mood Indigo.

VOA: special.2009.11.15

Some stepped back from their computer monitors to reminisce about 2007, when they said the mood was more electric as the blue chips hit new highs.

WSJ: Dow Keeps Hold on Record