no-brainer 与 沾某人光

no-brainer 可不能想当然以为是“没脑子的人”，那就闹笑话了。英文里的解释是Something easy to do or solve that requires little or no thinking. 所以不是没脑子，是根本用不上脑子就可以搞定的事情。

这是个名词短语。How do we decide the salary raises for next year? It's a no-brainer, I'm telling you now, 'cause they cut our budget. So nobody gets a raise, you know?

沾某人的光，本义上沾光是指物体受到光源照耀而带有光泽。用在人身上引申的意思就是由于别人的缘故，凭借外人的某些东西为自己谋得利益或好处（有形或无形的）。英文里有个类似的意译表达，on one's coattails. 英文的解释是，benefiting from another's merits,success or popularity. 从他人的各种“亮点”中受益，这就是沾光呗。

coattails指的是西方近代男士燕尾服的后摆，这个短语为什么有这个意思呢，其实就是那个年代的一种画面感，讽刺那些在聚会等社交场合跟在名流后面蹭风头的跟班们，就像挂在(hang)或者骑在(ride)别人燕尾服后摆上甩不掉的寄生虫。

这是个副词性短语，常见搭配的动词是 hang 和 ride，Bill isn't very creative, so he rides on John's coattails. Some people just have to hang on somebody else's coattails.

与其他动词搭配也可以，有时也可不用on. 只要有coatttails就好了。He is so famous only because he has been on his father's coattails.  He has been riding his father's coattails for almost his entire life.