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					Research in my lab has focused on how food becomes contaminated, and we've done some work on this particular piece of wisdom. 2018年12月四级真题(第三套)阅读 Section B
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					We found that the number of bacteria transferred to either kind of food didn't depend much on how long the food was in contact with the contaminated surface——whether for a few seconds or for a whole minute. 2018年12月四级真题(第三套)阅读 Section B
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					We wanted to know if the length of time food is in contact with a contaminated surface affected the rate of transfer of bacteria to the food. 2018年12月四级真题(第三套)阅读 Section B
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					When a carpet was contaminated, less than 1% of the bacteria were transferred. 2018年12月四级真题(第三套)阅读 Section B