This is the present value of $1 in one time period, which I'm taking to be a year.

这就是一美元在一段时期内的现值,我只是将一美元持有一年

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In other words what happens to people's health as they lose weight and then regain it repeatedly over a period time?

换言之,在一段时期内反复增重减重,对人们的健康有什么影响

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