Past discovery
Past
Future
Deduction of certainty (I'm sure it was not)
Emphasis on prolongation of action
Present process
Emphasis on result in present
Hypothetical situation
Present
Deduction of certainty (I'm sure it is)
Emphasis on recepient of action
Present-Future
Future plans
Unreal Present
Arrangements
Emphasis on receiver of action
Present with continuity from past
Timetable
Real Possibility
Present with reference to past