Too busy getting on with life, many seemed to have jettisoned courtesy as an optional extra.

由于过于忙的要应付生计，许多人似乎投弃了谦恭，把它当成是可选择的额外部分。

The system includes speakers and an amplifier. A projector security cage is an optional extra.

该系统包括还包括一个扬声器和放大器。

A simple idea would be to sell access to the quiet carriage as an optional extra when the ticket is bought.

只需在售票时为安静车厢额外收费，就可轻松实现这一想法。

So, in terms of practicing this weekend, I mentioned that instead of getting a problem-set today, what I am going to be Posting is optional extra problems.

而对于这周的练习，我曾经说过今天将不会布置作业，但是会布置一些额外的习题。

The integrated child seat in the Passat has been awarded a prize by the German motorist association ADAC and is available as an optional extra for 255 euros (two seats for 445 euros).

解放油罐车座位的综合产物在帕萨特荣获奖由德国ADAC司机协会和可作为一个可有可无的为255欧元（两张445欧元）。