小空格
$abc \ abc$
abc abcabc \ abcabc abc
中空格
$abc \quad abc$
abcabcabc \quad abcabcabc
大空格
$abc \qquad abc$
abcabcabc \qquad abcabcabc
对比
abc abcabc \ abcabc abc
abcabcabc \quad abcabcabc
abcabcabc \qquad abcabcabc
$abc \ abc$
$abc \quad abc$
$abc \qquad abc$