美 [ˈletɪŋ daʊn]
泌乳：指哺乳动物通过乳腺分泌的乳汁给幼体喂食的行为。
the act of causing something to move to a lower level
同义词： lowering
回火
松弛回火(letting down), 此释义来源于网络辞典。
... lengthwise angle 纵向折角 letting down 回火 level luffing 水平变幅 ...
... diminution 减少 letting down 下滑 sullen 愠怒的 ...
He was afraid of letting down his parents, so he studied hard to get into university.
他很害怕让他的父母失望，所以努力学习考上了大学。
I have a dread of letting down Ray's contributors, who are expecting to see their work in his magazine.
我很害怕自己会让雷的撰稿人们失望，他们都希望看到自己的作品出现在他的杂志上。
It hurts me deeply to see people fail to cultivate! Aren't you letting down the vows you made upon first leaving home?
我见到不修行的人，觉得非常痛心，这岂不是辜负自己当初出家时所发的愿吗？
"It's really standing firm and not letting those kinds of questions get you down because they are going to come."
VOA : standard.2010.02.25
And, yes, it is a form of letting down your teammates and the fans.
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But that movie, which took so long to get made, ended up letting down legions of fans.
The HSE's principal inspector for the West, said some sites were letting down the rest of the industry.