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Bacteria are carried by various 'media', which can include raw food, moist surfaces where bacteria have been left, our hands or skin and from coughing or sneezing (打喷嚏).
2018年12月四级真题（第三套）阅读 Section B
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Each session has a theme, and participants are given a variety of materials and prompts and asked to cover surfaces with their thoughts and art.
2019年6月四级真题（第三套）阅读 Section C
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However, bacteria have been shown to live on cabin surfaces, so wash your hands frequently.
2019年12月四级真题（第三套）阅读 Section A
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Research or common sense tells us that the best thing to do is keep your hands, utensils and other surfaces clean.
2018年12月四级真题（第三套）阅读 Section B
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These microscopic layers of deposits containing bacteria are known as biofilms and they are found on most surfaces and objects.
2018年12月四级真题（第三套）阅读 Section B