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By giving everyone nasal drops containing either a cold virus or a particular flu virus. By giving everyone a medicine that help lessen the probability of catching cold. By giving everyone an injection boosting immune function. By investigating everyone’s characteristics, interests and hobbies.
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how many this helped how much this helped how often did this help how much did this help
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didn’t he did he isn’t he is he
didn't he did he isn't he is he
should have failed couldn’t have failed might have failed shouldn’t have failed
should have failed couldn’t have failed might have failed shouldn’t have failed
did they didn’t they did it didn’t it
did they didn’t it did it didn’t they
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