原文：
Until 2001 the phenomenon of the negative refraction has been experimentally verified first by using artificial left-handed materials realized by periodic arrays of split ring resonators (SRRs) and wire strips .
编辑意见：
In the 1st paragraph of section 1 “Until 2001 the phenomenon of the negative refraction has been experimentally verified” if you mean “until 2001” (2001 is the ending point), then “has been” has to be changed to “had been”. If you mean “since 2001” (2001 is the starting point) then there is no problem with “has been”.
Not until 2001 was the phenomenon of the negative refraction experimentally verified.
OR:
The phenomenon of the negative refraction was experimentally verified for the first time in 2001.
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