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One of the main things enforced by strict is that you need to declare your variables, typically with my.

Here is the code you provided, in the <code> tags:

#use strict;
#use warnings;

open (FILE, 'german.txt');
@words = <FILE>;
$num = int rand(@words);
($article, $noun) = split(/ /, $words[$num]);
chomp($noun);
print "Who is the article of $noun:";
chomp($resp = <>);
if ($resp eq $article) {
    print "Correct!";
} else {
    print "The correct answer is $article!"
}
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A few problems:

1. You need to declare the variables with my
2. You should check that the file was opened successfully

Here is a corrected version

use strict;
use warnings;

open (FILE, 'german.txt') or die "Failed to open german.txt - $!";
my @words = <FILE>;
my $num = int rand(@words);
my ($article, $noun) = split(/ /, $words[$num]);
chomp($noun);
chomp($article);
print "Who is the article of $noun:";
my $resp = <>;
chomp $resp;
if ($resp eq $article) {
    print "Correct!";
} else {
    print "The correct answer is $article!"
}
[download]