let down
1．descend；lower 放下
Please let down the blinds．请把百叶窗放下。
2．disappoint；betray 使…失望
The team felt that they had let the coach down．队员们觉得他们让教练失望了。
We've been let down so many times by the importers，who always seem to be late delivering the goods．进口商们已多次令我们失望，他们似乎总是要推迟交货。
He won't let you down；he's very reliable．他不会让你失望的，他很靠得住。
3．slow up；slacken 慢下来；松懈
The horse let down near the end of the race and lost．那匹马在近终点时慢了下来，所以输了。
Don't let down even if the going is good．即使在顺利的情况下也不要松劲。
We must not let down our vigilance against the enemy．我们决不可放松对敌人的警惕性。
4．lengthen；make（clothes）longer延长；把（衣服）放长
She let the dress down，several centimetres．她把这件衣服放长了几厘米。
5．loosen and let fall 披散
She let her hair down．她披散着头发。
6．deflate 放气
A naughty boy has let down the back tyre of my bike．一个顽皮的男孩把我自行车后胎的气给放了。