Congress has obstructed efforts to create a more straightforward visa for agricultural workers that would let foreign workers stay longer in the U.S. and change jobs within the industry.

美国国会一直在为创建更直接的农业工人签证设阻，这种签证可以让外国工人在美国停留更长时间，还能在该行业内更换工作。

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As a result, farms have grown increasingly reliant on temporary guest workers using the H-2A visa to fill the gaps in the workforce.

因此，农场越来越依赖使用 H-2A 签证的临时外籍劳工来填补劳动力缺口。

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South Korea offers a special visa to foreign technology workers that allows them to enter and leave the country freely for three years.

韩国签证提供了一个特殊的外国技术工人，使他们能够进入和离开该国三年自由。

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Charles Grassley, a Republican senator, responded with a proposal to prohibit any company that had laid off Americans from hiring visa workers at all.

ECONOMIST: Skilled immigration

Under these circumstances it is no surprise then that domestic workers who compete against these visa holders sometimes complain that their wages are below market value, since the firm is effectively granted a monopoly over visa workers, and as a result able to grab a portion of the higher productivity an immigrant attains by moving here.

FORBES: How To Improve Immigrant Visas

It aims to strengthen border security while raising the cap on visas for high skilled workers and establishing a new visa program for low skilled workers on America's farms and elsewhere.

CNN: Immigration reform clears key Senate hurdle