"Nobody can put Numbers on the flows of Chinese into Russia because just about all of it is undocumented," though much of it is probably temporary, or "circular," migration, says Quillin.

“没有人能够了解流入俄罗斯的中国人人数，因为几乎所有中国人均未经正式登记，”虽然大部分中国人均为临时入境或“循环”流动，Quillin表示。

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Given the difficulty of comparing the pros and cons of even legal migration, assessing the undocumented will be impressionistic at best.

ECONOMIST: Illegal immigrants

Like Mr Bush, they support a proposal, drafted in the Senate with bipartisan support, which would combine tighter border security with increased legal migration and steps to regularise the status of undocumented migrants.

ECONOMIST: Latin America and the United States