At the risk of being a terrible off topic HN commenter,

> He's taught

> He's explained

> He's taught

I'm not sure if it's technically correct (or incorrect) grammar, but I (native English speaker) found these constructs to be really difficult to parse. I wasn't sure whether it was a contraction of "he is" or "he has" as both made sense (though the second point later has context that points to "he has").

I'm not bothered, and I hope no offence is taken by this, I just thought it was mildly fascinating. I don't think I often see that "He's" contraction in English.