6. aver / avert / averse / avow / advent /advert

aver: to say something in a very strong and definite way

avert: to prevent (something bad) from happening

averse: having an active feeling of repugnance or distaste

avow: to declare or state (something) in an open and public way

advent: second coming

advert: announcement; notification

7. feckless / reckless

feckless: weak and ineffective; worthless;irresponsible

reckless: not showing proper concern about the possible bad results of your actions

8. mean / mien

mien: a person’s appearance or facial expression

9. humdrum / conundrum

humdrum: dull, boring, and ordinary

conundrum: a confusing or difficult problem

10.immune / immure / inure

immure: to enclose within or as if within walls

inure: to cause (someone) to be less affected by something unpleasant