blue表示情绪低落
示例
A：She looks blue.
B：Yes, she took every opportunity, but failed at last.
A：她满面忧伤。
B：是啊，她抓住了每一个机会，可最后还是失败了。
A：She looks blue. What's wrong?
B：Nothing, maybe she is tired.
A：她看起来很伤心，怎么啦？
B：没什么，可能累了。