When the water vapor touches the cool surface of the cup, condensation (the change of a gas to a liquid) occurs and water drops form.
(the water vapor; touches; the cool surface of the cup) (condensation; occurs; T:When the water vapor touches the cool surface of the cup) (water drops; form; )
the water vapor condensation water drops
touches occurs form
the cool surface of the cup
T:When the water vapor touches the cool surface of the cup