What's the opposite of thick?
thin
What's the opposite of difficult?
easy
What's the opposite of deep?
shallow
What's the opposite of high?
low
What's the opposite of healthy?
unhealthy
What's the opposite of dangerous?
Safe.
What's the opposite of hilly?
flat
What's the opposite of old (person)?
young
What's the opposite of pretty/beautiful?
ugly
What's the opposite of fast?
slow
What's the opposite of sunny?
cloudy
What's the opposite of big?
small
What's the opposite of cheap?
Expensive.
What's the opposite of crowded?
quiet
What's the opposite of wet?
dry
What's the opposite of tall?
short
What's the opposite of hot?
cold
What's the opposite of heavy?
light