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To begin the introduction in order to describe the general background context, i.e. what is known already
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Present simple |
Zinc, an essential dietary constituent, is a co-factor of antioxidant enzymes (47) |
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To show how the problem has been approached from the past until the present day
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Present perfect |
1- Lower plasma zinc concentrations have been reported in obese subjects (47); 2- A direct correlation has been observed between zinc intake and incidence of chronic hypertensive diseases (47) |
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To end the introduction, the authors present what they will do in the remaining sections of their paper (question/hypothesis)
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Present simple/Past simple |
1- The goal of this study is to provide …. (48); 2- We hypothesized that … (16); 3- We tested the hypothesis that …. (16); 4- The research presented here aimed to ….(49); 5- We examine….(50) |
