John,it's ---- bad manners to blow your nose at -----table

John,it's ____ bad manners to blow your nose at _____table
为什么两空都不填?而不是填a/the?
_____runners won medals.They won_____prizes
A.The first two ;two first
B.Two first;the first two
C.Fist two;the first two
D.The two first;the two first
为什么选A?
He punished his students______for being too nosiy in class
A.a second time
B.the second time
C.for a second time
D.twice time
为什么选A?C和A有什么区别?