您可以使用 explode ， foreach 和 str_replace :

You can do this using explode, foreach and str_replace:

<?php
# Keywords
$keywords_str = 'tv nice';

# String
$string = 'My tv is nice';

# Operation result(to not modify $string)
$result = $string;

# Split $keywords by spaces into array of single keywords
$keywords = explode(' ', $keywords_str);

# Loop keywords array
foreach($keywords as $keyword)
{
    # Replace every keyword occurence to make it bold
    $result = str_replace($keyword, "<b>$keyword</b>", $result);
}               

echo $result;

?>

结果将是:

我的电视是好