答：display隐式的变为block。
<!DOCTYPE html>
<html lang="en">
<head>
<style>
span {
float: left;
}
</style>
</head>
<body>
<span>Lorem ipsum dolor, sit amet consectetur adipisicing elit. Odio, ea accusantium distinctio libero obcaecati
soluta nesciunt? Ipsa sapiente nam omnis, dicta iure maiores esse at doloribus illum, delectus soluta
corrupti.</span>
</body>
</html>已知span为行级元素，设置float:left后：