Editor on call: using then/than and lose/loose

Today I'm addressing two pairs of "spelling challenge" words a reader asked me to discuss. These pairs perplexed me a bit, because they aren't actually homophones. But because they are "kissing cousins" so to speak, pronunciation-wise, you might have gotten mixed up somewhere along the line about which word is which.
Then Pronounced then (voiced th, short e like in elephant); rhymes with pen, when, den, wren.

adv. - at that time; soon after, following; in addition, besides. In th...