Phrasal Modals of Obligation

First of all, a "modal" is a type of verb.  It is sometimes called an auxiliary verb or helping verb and is different than a regular verb such as "work", "play", "walk", etc.   These verbs include "may, might, must, can, could, will, would, shall, should, need to, have to, etc.".  They are used to express ability, permission, necessity, advice, obligation and possibility.

For this lesson, we're going to look at: should have, was supposed to, and needed to for describing obligations in the past

Let's look at some sentences:

  • I should have stayed home and studied!  (It was a good idea, but I didn't do it).
  • I shouldn't have eaten so much candy.  (This was not a good idea, but I did it anyway and now I regret it)
  • I shouldn't have gone to bed so late; now I have a headache.  (I regret going to bed so late)
  • I should have apologized for being late to the meeting.  (Being late was rude and I regret that I didn't apologize for my tardiness.)

Note:  "should have" or "shouldn't have"  is used with a past participle form of the verb:  should have stayed; shouldn't have eaten; shouldn't have gone; should have apologized

  • I was supposed to call my friend when I arrived. (It was expected, but I didn't do it.)
  • I was supposed to turn in my research paper today.  (It was due and my professor expected it, but I didn't finish on time).
  • I wasn't supposed to tell anyone about the surprise.  (I was expected to keep it a secret, but I told 3 people)
  • We weren't supposed to stay out late (The curfew was 10 PM, but we stayed out until 1 AM)

The verb after "supposed to" is in the simple tense form:  supposed to call

Obligation:  "had to..."

  • I had to leave early because I wasn't feeling well.  (I didn't have a choice about this because of the way I felt)
  • I had to wear a uniform in school.  (this was the rule and we were forced to do this)
  • I had to stay late and finish my report.  (There was a high obligation to finish my report)

Note:  When using "had to" for this obligation, we are focusing on the idea that something was completed or was accomplished.  If someone says "I had to..." then most likely they did it.   Let's say you had an assignment due yesterday.  This is a high obligation or a requirement.  However, if you didn't do the assignment, you cannot say I had to turn in my assignment, because you actually DIDN'T turn it in. (It didn't get done).    The more appropriate response is:

  • I was supposed to turn in my assignment yesterday.   OR 
  • I should have turned in my assignment yesterday.

NO obligation:  "didn't have to.."

  • I didn't have to stay home and study.  (There was no obligation to stay home and study because I was already prepared.)
  • I didn't have to give my teacher a gift, but I wanted to.  (No obligation to do this.)
  • I didn't have to take the stairs at work, but I wanted to get some exercise.  (I could have taken the elevator instead)

Obligation:  "needed to..."  OR

No Obligation:  "didn't need to..."

  • I spent a lot of money last weekend because I thought I needed to buy more fashionable clothes.  (I thought this was necessary)
  • I left the party early because I needed to finish my project for school.  (It was necessary to leave the party early because I needed more time to finish my project)
  • I needed to go to the gym after work.  (this is necessary, so I most likely went to the gym)
  • I know you liked the movie but you didn't need to tell me the ending!  Now you've spoiled it for me.  (It wasn't necessary to tell the ending of the movie.)
  • Maria didn't need to spend so much money on my gift! (It wasn't necessary to get me an expensive gift)

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