Test pilots try to push the envelope.

试飞员尝试挑战极限。

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'It's my job here to push my staff to push the envelope and think about the global automotive future from Beijing.'

我在这里的职责就是敦促手下员工开拓思路，站在北京畅想全球汽车业的未来。

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Sometimes they have to push the envelope to see whether a newly designed plane really can meet the limits the designers planned.

有时候他们必须让新设计的飞机挑战极限，以便测试飞机是否真能达到设计人员所设定的安全极限。

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"It's absolutely necessary that we continue to push the envelope in terms of try to develop new innovative and more natural ways of effectively treating arthritis."

VOA: standard.2010.08.11

Brandon Gutman: What is American Express doing in 2011 to push the envelope on customer service?

FORBES: Why American Express Is Raising The Bar On Customer Service

For us to push the envelope of what can be done in Antarctica, that felt good.

BBC: Polar express

With each new film, audience expectations rose as Nolan continued to push the envelope of super hero storytelling.

FORBES: Christopher Nolan Delivers Super Hero Perfection With The Dark Knight Rises