额外的空<option>从哪里来？

<?php 
$salaries = array(1000,1500,2000,2500,3000,4000,5000,6000,7000,9000,12000,18000,30000); 
$str = ''; 
foreach($salaries as $salary) 
{ 
    $str .= "<option value=\"$salary\">$salary+</option>"; 
} 

function populateSalary() 
{ 
    $salaries = array(1000,1500,2000,2500,3000,4000,5000,6000,7000,9000,12000,18000,30000); 
    $str = ''; 
    foreach($salaries as $salary) 
    { 
     $str .= "<option value=\"$salary\">$salary+</option>"; 
    } 
    return $str; 
} 
?> 
<select id="salaryExpect" name="salaryExpect"> 
    <option value="-1">--<option> 
    <?php echo populateSalary(); ?> 
</select>

请参阅代码中没有<option> </option>这样的空白选项，但输出中存在足够奇怪的选项。额外的空<option>从哪里来？

可以看看这里： http://maishudi.com/test3.php

来源

2009-09-21 omg