envelope

英 ['envələʊp; 'ɒn-]

used to denote calculations or plans of the most sketchy kind

粗略的估算（或计划）

a proposal drawn up on the back of an envelope.
一项粗略的提议。

(informal)approach or extend the limits of what is possible

(非正式)几近极致

these are extremely witty and clever stories that consistently push the envelope of TV comedy.
这些故事极其诙谐巧妙，总是将电视喜剧推向极致。

To increase the operating capabilities of a technological system.

增强技术系统的运转能力

1. Return the enclosed Donation Form today in the prepaid envelope provided.: 请于今日将随函附上的捐款表格用所提供的邮资预付的信封寄回。

2. Under the newspaper, atop a sheet of paper, lay an envelope.: 在报纸下面的一张纸上放着一个信封。

3. The envelope has been tampered with and then taped shut again.: 信封被人动过手脚，然后又用胶带封上了。

4. Liz picked up the blue envelope and turned it over curiously.: 莉兹拿起蓝色信封，好奇地翻过来看。