a) Dangerous - safe
extraordinary - usual
incredible - ordinary
real - unreal
serious - funny
polite - impolite
ancient - modern
tall - short
handsome - ugly
athletic - non-athletic
strong - weak
hard-working - lazy
obedient - naughty
noisy - quiet
b) to agree - to disagree
to put on - to take off
to forget - to remember
to be right - to be wrong
to start - to stop
to repair - to break
to love - to hate
to find - to lose
to close - to open
to give - to take
to sit - to stand
to talk - to keep silent
extraordinary - usual
incredible - ordinary
real - unreal
serious - funny
polite - impolite
ancient - modern
tall - short
handsome - ugly
athletic - non-athletic
strong - weak
hard-working - lazy
obedient - naughty
noisy - quiet
b) to agree - to disagree
to put on - to take off
to forget - to remember
to be right - to be wrong
to start - to stop
to repair - to break
to love - to hate
to find - to lose
to close - to open
to give - to take
to sit - to stand
to talk - to keep silent