A fairly simple regex will take care of that.

{
    local $_;
    while (<>) {
        /it (.*)[.?,]$/i and print $1, $/;
    }
}
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Update: ++davidrw's points are accurate and easily corrected. I'll follow his lead and leave the modifications as an exercise. Also, you may wish to allow for any amount of any sort of whitespace after "it".

Hmm.. does seem like homework as Grandfather suggested, so i won't post a regex, but instead these points for OP to consider (perldoc perlre) with regards to the above regex:
• That will match the word "hit", and won't match "hit it." -- (hint: word boundary)
• If there's multiple "it" words in the line, what do you want to print? (hint: greediness)
• Should the trailing [.?,] be printed as well?

I have searched far and wide and I can't find how to accomplish the printing of the trailing char from character set .?,