原书 PDF 第 484 页
in the evening/on the evening
（1）What do you usually do ____? A. in an evening B. in the evening C. on the evening(全国高考)
(2) Surprisingly, the weather report on the evening before the storm said there would be strong winds, but not a hurricane.
试题(1)要求选 B(in the evening)，不能选 C(on the evening)，而句 (2) 却使用了 on the evening。这是怎么回事呢？
in the evening 是笼统地指“晚上”，而 on the evening 是指某个特定的晚上。在句(2)中，the evening 后面有定语 before the storm，说明 the evening 是指一个特定的晚上，故必须用介词 on，而不能用介词 in。
evenings
It's a part-time job, so I only work evenings.
如何分析句中的 evenings?
可以把 evenings 看作是其前省略了介词 on 的介词短语。即(on) evenings 作时间状语：... so I only work(on) evenings.
也可以把 evenings 看作是名词, 直接作状语。类例:
(On) Sunday(s) we usually go for a walk. 我们通常在星期日出去散步。
I've got to work evenings! 我必须晚上工作!
[附注]有的英语词典把 evenings 定为副词。
Evenings, we sit at home and watch television. 晚上,我们坐在家里看电视。
Monday evening he turned up at the flat.
Monday evening 是否应改为 On Monday evening?
在 evening 之前有 Sunday, Monday... 作定语时, 其前的介词 on 在非正式语体中是可以省略的, 见 on Sunday evening/Sunday evening。
of an evening 见 of (of an evening)
( on ) Sunday evening 见 in the morning/on the morning