允许（某人）下车，离开（公共交通工具）：指允许某人在公共交通工具上下车或离开。
宽恕，放过（犯错误或违法的人）：指对犯错误或违法的人不予惩罚或轻罚。
引爆，释放（压力等）：指引爆或释放某物，使其以强大的力量爆炸或释放出来。
let off // [ letting lets ]
动词词组 If someone in authority lets you off a task or duty, they give you permission not to do it. 免除 (任务或义务)
I realized that having a new baby lets you off going to boring dinner parties.
我意识到，生了个孩子你就可以不参加无聊的宴会了。
动词词组 If you let someone off, you give them a lighter punishment than they expect or no punishment at all. 宽恕
Because he was a Christian, the judge let him off.
因为他是一个基督徒，法官宽恕了他。
动词词组 If you let off an explosive or a gun, you explode or fire it. 放 (枪炮等); 使爆炸
A resident of his neighbourhood had let off fireworks to celebrate the revolution.
他邻里的一个居民燃放了烟花来庆祝革命。
... let in：让进来；放进；漏水 let off：让（某人）上岸或下车；放（炮、烟火等），放过；原谅 let on：泄露秘密；讲；承认 ...
... let alone更别提;不打扰 let off排放;放(炮)，开(枪) let out放掉(水等)，发出 ...
... let in让…进进；放…出来 let off放（炮）；开（枪）；宽恕 let out放失落（水等），发出 ...
放出；准许…暂停工作；宽恕
The mother said she would let off her son washing the dishes if he could finish his assignment before supper.
母亲说如果儿子能在晚饭前完成作业，她就不让他洗碗。
She was let off with a warning.
她被从轻处罚，只是受了个警告。
A resident of his neighbourhood had let off fireworks to celebrate the revolution.
他邻里的一个居民燃放了烟花来庆祝革命。
Jackie Robinson had difficulty on and off the baseball field, but he did not let that interfere with his game.
VOA : special.2009.04.05
All right. So, let's pick up where we left off, first of all we're still on the hydrogen atom from Monday.
好，让我们从上次停下的地方讲起，我们还要讲周一讲的氢原子。
化学原理课程节选 : 麻省理工公开课
I don't know what this tells us about David and Nina, but don't let them off the hook quite yet.
从大卫和妮娜的协调中得不出什么结论,这事儿还没结束呢
博弈论课程节选 : 耶鲁公开课
Let's see if I can name a few off the cuff, or without any preparation.
VOA : special.2010.05.02
On Friday,Galina Petrovna, a 64-year-old Moscow nanny, let her two year old charge cool off with a dip in a public fountain.
VOA : standard.2010.07.23
"The problem is that so-called 'historic' rapes are being let off too lightly, " she adds.
BBC: NEWS | UK | Magazine | How can a rapist only be cautioned?
Instead, he complained that Mr. Gingrich's tax simplification plan would let off rich guys.
To let off steam, she turns her real-life frustrations into laughs at a stand-up comedy club.