As a little brainstormer, suppose you have a variable with the following test content:

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$str = @"
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
"@

Here is how you can print all odd lines from it:

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$f=0; $str.Split("`n") | % { if($f = !$f) { $_ } }

Or, if you want all even lines, change the initial $f value to 1:

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$f=1; $str.Split("`n") | % { if($f = !$f) { $_ } }