Ref: http://dictionary.cambridge.org/us/grammar/british-grammar/inversion Introduction Inversion happens when we invert (reverse or swap) the normal subject-verb order. Though this topic has been covered in other places in LEWWWP, I am including it here so I can find it easily and because I try to be more concise and succinct than other people.
Watch this video.
Watch this video. Essentially, it is saying that it is now acceptable to use “they” as a “singular”, gender-neutral pronoun. We call this the “singular they”. Everyone should do their best. I would like each person to do their best. (not his best, not his/her best, just their best)