Possible Duplicate:
mysql_fetch_array () espera que o parâmetro 1 seja recurso, booleano fornecido em select

// o erro está na linha 13

$questions =$_POST['question_text'];

$checkquestion=mysql_query("SELECT question_text FROM questions LIKE '$questions' ");

if(mysql_num_rows($checkquestion)) { //line 13
echo "Question exist.";
                   }
else{

mysql_query("INSERT INTO questions (question_text,field_name)
VALUES ('$_POST[question_text]','$first_word')");
echo "Question saved";
                   }