Melamine was approved to be a 'food contact substance' in the late 1960s or early 1970s.

上世纪60年代末、70年代初，三聚氰胺曾被批准为“可与食品接触的物质”。

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This substance should not come into contact with food.

这种物质切莫与食物接触。

《牛津词典》

Both substances also contained a substance that would mark any mosquito that came in contact with it.

这两种喷雾中都含有一种物质，可以标记出接触过这种喷雾的任何蚊子。

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On September 25, the woman had contact with a letter or package with a white powdery substance and began experiencing symptoms of cutaneous anthrax three days later.

CNN: Cutaneous anthrax most common, most survived

Even less than diplomats do they know languages, or the substance of any subject matter that would lead to natural contact with sources.

CENTERFORSECURITYPOLICY: Freedom Flame 2013