S. studies have shown that 30 percent of the pig population has antibody evidence of having had H1N1 infection. More specifically, 51 percent of pigs in the north-central U.
在美国，有30%的猪被检测出抗体，表明它们被H1N1感染过，而在美国中北部，这个比例是51%。
Pig lift method with U-shape double strings is easy to be limited by size of casing and very complicated in construction operation process. Thus, the large restrictions exist in the field application.
球塞气举方式采用U型双管柱易受套管尺寸限制，且施工作业较为复杂，其应用受到较大限制。
Pig lift method with U-shape double strings is easy to be limited by size of casing and very complicated in construction operation process. Thus, the large restrictions exist in the field application.
球塞气举方式采用U型双管柱易受套管尺寸限制，且施工作业较为复杂，其应用受到较大限制。
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