He said diners drank only water and never paid the optional service charge.

经理表示餐厅的客人只饮用水，也不会付任何其他服务费用。

youdao

This pattern may also be used when the addition of optional parameters can speed up the processing of the service request.

当添加可选参数能够加速服务请求的处理时，也可以使用这种模式。

youdao

The service provider catalog is an optional part of the service discovery process.

服务提供者目录是服务发现进程中的一个可选的部件。

youdao

The app also features an optional upgrade service from Evoz that provides advanced monitoring, cry notifications via text or email, cry history information, and analysis of baby's crying and sleep patterns.

ENGADGET: Belkin WeMo Baby monitor lets you listen to Junior via an internet connection and an iOS device

Nominet, the organisation that oversees UK web addresses, has put the brakes on plans to launch an optional new service for sites ending with ".uk".

BBC: Shorter .uk web address idea shelved by Nominet

Match is an optional addition to an existing free service called iTunes in the Cloud, which covers only songs you bought from Apple's iTunes store, or which you buy there in the future.

WSJ: Apple's Music Service Stores All Your Songs Without Alot of Slow Uploads