my $html =<<'HTML';
<ol>
<li>
Question1? Answer1.
<li>
Question2? Answer2.
<li>
Statement. Response to statement.
<li>
Question3?
<pre>Answer3.</pre>
</ol>
HTML

my (@questions, @answers);

while ($html =~ m{    <li>
                      \n    
                      (
                        [^<]+
                      )  
                 }xmsg  
       )
{
    my $text = $1;

    if ($text =~ / [?] /xms ) {
        my @pieces = split / (?<=[?]) \s* /xms, $text;
         
        push @questions, $pieces[0];

        if (@pieces == 2) {
            chomp $pieces[1];
            push @answers, $pieces[1];
        }
        else {
            $html =~ m{   \G
                          <pre>
                          (.+?)
                          </pre> 
                      }xms;

            push @answers, $1; 
        }
    }
} 
print "@questions \n";
print "@answers \n";

--output:--
Question1? Question2? Question3? 
Answer1. Answer2. Answer3.