This document discusses past modals and phrasal modals used to describe obligations in the past, including: should have, was supposed to, had to, and needed to. It provides examples of how each modal is used to indicate: strong obligation, expectation, advisability, necessity, and no obligation in past situations.

1. Modals of Obligation
Passages 1, Unit 2

2. Past modals and phrasal modals
 To describe obligations in the past:
 should have
 was supposed to
 had to
 needed to

3. In which situations the plants were watered?
 I was supposed to water my neighbor’s
plants.
 I had to water my neighbor’s plants.
 I should have watered my neighbor’s plants.
 I needed to water my neighbor’s plants.
 I didn’t have to water my neighbor’s plants.

4. I should have stayed home and studied!
It was a good idea, but I didn’t do it.

5. I was supposed to be studying this weekend.
It was required, but I didn’t do it.

6. We had to wear a uniform.
We were forced to do this.

7. I didn’t have to go with my friends, but I did.
There was no obligation.

8. I thought I needed to have more clothes.
I thought it was necessary.

9. Strong obligation
 To show that there was no choice
about doing the action. USE:
• was / were to
• had to
My parents had to go to
school on Saturdays.

10. Expectation
 There was a general
USE:
expectation that an action • be supposed to
was required or prohibited.
She was supposed to talk to
my professor after class.
He wasn’t supposed to drive
the car to school.

11. Advisability
 There was a good idea or a correct action in a
particular situation, but it was or was not done.
USE:
• should (not) have
He should have taken better notes in class.
She shouldn’t have bought such an
expensive jacket.

12. Necessity
 The action was considered to be necessary or
unnecessary; however, unlike “had to”, there is
a choice about doing or not doing the action.
I needed to make an USE:
appointment with the • needed to
counselor. • didn’t need to
I didn’t need to buy the text book,
but I thought it looked interesting.

13. No obligation
 There is complete choice about
doing the action.
USE:
• didn’t have to
I didn’t have to take piano
lessons, but I wanted to.