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His grandfather made him __________ hard when he was small

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Scientists has just come up __________ a solution to hearing loss.

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Do you know what is the cause __________ pollution?

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Could you list some non-point source __________?

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I can’t hear your voice __________ I’m wearing an earplug

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My mother has to measure blood __________ every month.

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 __________ pollution is harmful or annoying level of noise, as from vehicles, industry activities, etc.

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What would you do if a factory in your neighborhood __________ untreated water into the river?