"Some cases,there are lobbying groups that are actually so successful and have so much influence they're able to write bills,propose bills, for members of Congress.

VOA: special.2010.09.27

Why is it difficult in some cases to produce a vaccine when we've been successful in so many others?

为什么某些疾病的疫苗很难研制,即使我们已经成功生产了很多种疫苗

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