3.6.1.1.1: Past Modals for Single Actions in the Past- The Simple Past Tense

Past Modals for Single Actions in the Past:  The Simple Past Tense

       The past tense of must, have to, and has to is HAD TO. 

Had to                Obligation or necessity in the past            Past of must,
(hadda)                                                                                    have to, and has to

He had to take his daughter to the hospital
last night because she had a high fever.
He had to change the flat tire on his car last night.
We had to pay our income taxes last year before April 15^th.
I had to drive my wife downtown because she is afraid to drive in the city by herself.
My son had to memorize a lot of music for his concert.

________         _______________________________             ____________

Must have + past participle                Past conclusion or supposition only;
(musta)                                                  Never a past obligation: For past
                                                                obligations, use had to.

Sara is a teacher; therefore, she must have graduated from a four-year college.
                                                                                                   (conclusion)

There was some candy on the table and the children were in the room. Now the candy is gone. The children must have eaten the candy.  (conclusion)

She broke her leg playing basketball.  It must have hurt a lot.  (conclusion)

When I came home last night, the house was very clean.  My wife must have done a lot of housework during the day.  (conclusion)

However

While I was driving home, I got a flat tire, so I had to use my spare tire. (obligation)
The boy cut his head badly, so he had to go to the hospital.  (obligation)
The toilet broke last night, so I had to fix it right away.  (obligation)

Might have + past participle                Past situation – maybe it happened,
May have + past participle                    maybe it didn’t. We don’t know for sure,
Could have + past participle                 but we do know that it was possible.
(mighta, maya, coulda)

 The student didn’t come to class yesterday. She might have gone to the doctor’s.  She might have had an accident.  She may have gone shopping.  She could have stayed in bed.  I don’t know what happened for sure, but all of the above are possible.

My friend bought a lottery ticket.  He could have had the winning ticket.  I don’t know, but it is possible.

It might have snowed in the mountains last night.  Then again, it might not have snowed.
My sons might have seen each other this past weekend.  I don’t know if they saw each other.

Could have + past participle                       Past ability or capability to do something,
(coulda)                                                         but you chose not to do it. You had the
                                                                        opportunity to do something, but you decided not
                                                                        to do it.

A past possibility that you had an opportunity to do, but you chose not to do.

I lived in Asia for over 5 and a half years, but I never went to Korea. I could have gone there many times, but never did. 

I could have stayed in Europe in 1973, but I decided to return to the United States instead.

I could have become a history teacher if I had wanted to, but I decided to become an English teacher instead. 

You could have skipped school today if you had wanted to, but you decided to come.

My wife and I could have gone to a movie last night, but we were too tired and decided to bag it and not go.

                                                                                                                                                   
Should have + past participle                        Past obligation which you didn’t
(shoulda)                                                           do.  Something was the correct or right
                                                                            action to do, but you didn’t do it. 
                                                                            Something was a good idea or thing to do
                                                                            in the past, but you didn’t do it.  In other
                                                                            words, you made a mistake.

You were speeding in a car and a policeman saw you and gave you a speeding ticket. You should have slowed down, but you didn’t.

You had a test last week, but you didn’t study for it and you failed it. You should have studied for it, but you didn’t. 

My son went outside without his coat in the rain last week and he caught a bad cold. He should have worn a coat, but he didn’t.

The students shouldn’t have cheated on the exam, but they did.

I should have learned how to type when I was in high school, but I didn’t.  As a result, I am a slow typist. 

America shouldn’t have gotten into a war with Iraq, but it did.

Those boys shouldn’t have teased the new student in the class.  He started to cry and then everyone felt bad for him.