Form and rules
How it works
Simple aspect often presents facts, completed events or situations as wholes; continuous highlights activity, duration or temporary development.
Perfect aspect connects one time to an earlier time; perfect continuous additionally foregrounds ongoing/repeated activity.
In narratives, decide which past event is the main timeline, which is background and which happened earlier.
For future meaning, distinguish decision/intention/arrangement from activity in progress and completion before a deadline.
State verbs constrain continuous choices, so always consider lexical meaning as well as time reference.