Ok, so here's a shorter one, lifting the regex shamelessly from chomzee and perhaps more to the taste of citromatik ? ;) with a text file that has quotes as well...

"This is first sentence."
"This is second sentence."
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new code..

open (INP,"data.txt") || die "Cannot open data.txt\n";
while (<INP>) {
   print if (/^\"This\b/i and /\.\"$/ and !/\bfirst\b/i) 
}
[download]

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