Rules of thumb--choosing a tense

Rules of Thumb--Choosing a tense form
present and past tense forms

Pattern 1. Telling the truth

Always true	present tense forms	Susie swims in the morning. Water freezes at 32 degrees.
May no longer be true or hedging (implying a possible "no")	past tense forms	I loved my dog. If I had time, I'd help you.
	modals	They may come.

Pattern 2. Telling the time

Viewed from the present time	At the present time	present progressive simple present	(action verbs)I'm swimming in the pool (stative verbs) I think she's right.
	At an earlier time (no time expressed)	present perfect	I've finished the project.
	Started earlier and still going on	present perfect progressive	I've been working on this all day.

Viewed from the past time	At the past time	simple past	I ate at 5 p.m.
	At an earlier time	past perfect	I had finished when he came.
	Going on when interupted by another past event	past progressive past perfect progressive	I was washing the dishes when the bell rang. I had been washing the dishes when it rang.