However, efforts to control them are consistently undermined by the difficulty and expense of identifying mosquitoes-of which there are at least 3,500 species, many of them hard to tell apart.

然而，控制这些蚊虫的努力一直没有进展，关键在于鉴别蚊虫的难度和费用——至少有3,500种不同蚊虫，其中有不少很难加以区别。

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However, efforts to control them are consistently undermined by the difficulty and expense of identifying mosquitoes-of which there are at least 3, 500 species, many of them hard to tell apart.

然而，控制这些蚊虫的努力一直没有进展，关键在于鉴别蚊虫的难度和费用——至少有3,500种不同蚊虫，其中有不少很难加以区别。

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The de-normalization causes difficulty on data retrieval, analysis, and quality control.

这种不规范将为数据检索、分析和质量控制增加难度。

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Parkinson's disease is a disease involving destruction of motor control and loss of motor control, difficulty moving.

帕金森症会损害运动控制,丧失对运动的控制,变得行动困难

耶鲁公开课 - 心理学导论课程节选

While Mr. McNerney had approved the Dreamliner's heavily outsourced business model as a director, his allies say that much of the 787's initial difficulty was beyond his control.

WSJ: The Two Men Behind the 787

The Italian government does not want a foreigner to take control, but it would have difficulty using its golden share to block a European bidder.

ECONOMIST: Telecom Italia

The difficulty for marketers is creating the right kind of buzz and learning to control it.

ECONOMIST: Marketing: Building buzz | The