subject
this function can specify the string to be displayed after two words. "

mb_strimwidth(string, 0, "50", "...", "UTF-8");

question
but I now want to implement
so that he can find a paragraph and show only one paragraph
suppose this paragraph

:2 + 1 + 1

......

I want him to show "". It"s a perfect match! "and then stopped. Since the length of each blog is different, I want him to show only the first paragraph and not the second paragraph. How can this be judged?
the structure is as follows: