To me, "to seriously take" sounds strange not because it's split infinitive (there's nothing wrong with that), but "seriously" is not just an ordinary adverb he

To me, "to seriously take" sounds strange not because it's split infinitive (there's nothing wrong with that), but "seriously" is not just an ordinary adverb here: it's a complement of the verb _take_. "To take the work seriously" is a very different thing from "to take the work," while "to engage the work seriously" is basically the same as "to engage the work," except more seriously. And I don't think "seriously" (or a similar adverb), when used as a complement of "take," could just move around freely. Just like you can't say "I away chased the dog." * And, while we're at it, it's a bad idea to take seriously (haha) anyone who thinks split infinitives are wrong. You can find tons of amusing writings by actual linguists here: https://languagelog.ldc.upenn.edu/nll/index.php?s=Split+infinitive https://languagelog.ldc.upenn.edu/nll/index.php?s=Split+infi... (Spoiler alert: they think the rule is BS.)