<form class="search-form" action="/index.php" method="get">
    <input type="hidden" name="s" value="article">
    <input type="hidden" name="c" value="search">
    <input type="text" class="txt s" placeholder="请输入关键词" name="keyword" >
    <button type="submit" class="submit s">探索>></button>
</form>