So you should accept tighthead prop and loosehead prop respectively, ditto blindside and openside flankers.
There are other names for fly half which are correct - outside half or stand-off half are both terms used for the no 10 spot.
Centres should be inside centre (12) and outside centre (13)
Wingers should be left wing (11) and right wing (14)
And note spelling of centre - most people doing this quiz will spell it the British way.