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）。

Its rich feature set includes a touch panel for easy operation, an electromagnetic paper brake and pneumatically-driven reel transfer. Power-driven guide powering is available as an optional extra.

其丰富的功能包括一个易于操作的感应面板，电磁制动器和空气驱动的绕线架。

There also are plenty of optional safety equipments that you can get if you want some extra safety in the car.

如欲使爱车更加安全，另有大量的选装安全装备可供选择。

This parameter is optional: if you don't specify extra keywords, all is assumed.

该参数是可选的：如果您不指定额外的关键字，假定使用all。

Optional: for extra decoration, drizzle extra melted chocolate on top of the balls using fork.

可选：额外的装饰，使用叉子将额外融化的巧克力淋在花生球的顶部。