Would/Could/Might/Should + have

In previous lessons, we have learnt about different modal verbs, including their uses. They play an essential role in English grammar. Modal verbs help us speak clearly about the possibility, ability, certainty. In this lesson, we are going to study about past modal verbs. So, let’s begin. 

What are Past Modal Verbs?

Past modal verbs are used to talk about actions that were possible, permitted, obligated and able to be done, but they didn’t happen in the past. Using past modal verbs, we express our present feelings about the past. 

Past modal verbs are also called “modals of lost opportunity” because we usually talk about the opportunities we regret losing now. 

Past modal verbs include would have, should have, might have, and could have.  Before diving deeper into the past modal verbs let’s learn the difference between should, could, might and would. 

Should: 

We use should for giving advice/recommendation. 

• If you want to sleep early, you should wake up early. 
• If you want to achieve good grades, you should study harder. 

Could:

We use could for possibilities or ability.

• She could cause an accident if she drives like that.
• If you don’t get ready on time, we could be late for dinner.

Would:

We use would for imagining results.

• If I were fine, I would go for cycling.
• If she were rich, she would buy a bungalow.

Might:

We use might for probability or possibility.

• Her laptop might be in the study room.
• He might be stuck in traffic.

Structure of past modal verbs 

Formation of past modal verbs is easy.  To form these, you have to use could, would, should, might + have + past participle form of the main verb. Never use has or had to form a past modal.  In spoken English, past modal verbs are pronounced as woulda, coulda, shoulda. 

Could + have 

Could have along past participle means something was possible in the past, but it didn’t happen, or someone had the ability to do something in the past, but they didn’t do it. 

Example:

• I could have woken up early, but I decided to sleep for a while.
• I could have won the cricket match if I didn’t have a leg injury. 
• Angelina could have studied harder for her final exams, but she was too lazy. 
• Tom could have bought new books, but he borrowed it from his friend instead.

Couldn’t have is used to describe that something was not possible in the past even if someone wanted to do it. 

Example:

• I couldn’t have completed the assignment; the teacher didn’t give us enough time.
• He couldn’t have arrived any earlier. The traffic was jam since morning. 

Should + have 

Should have along past participle means something was a good idea, but it didn’t happen. Should have sounds like giving advice when we say it to someone else, and it is like regretting about something that you did or didn’t do when you are talking about yourself.

Example:

• I should have studied harder. (I have failed the exams now, and I am regretting)
• You should have asked me once before buying this dress. 
• He should have called me when he arrived. 
• They should have cancelled the plan if their friend’s mother was sick. 
• You should have helped your mother in the kitchen. 
• You should have added one more spoon of sugar in the tea.

Negative sentences are formed by adding ‘not’ after should.  Shouldn’t have means something was not a good thing to do but you did it anyway. 

Example:

• We shouldn’t have asked her about her exams. She sounded arrogant. 
• She shouldn’t have gone to London. She was sick. 
• He shouldn’t have said that to his friend, she is upset now. 

Would+ have 

Would have + past participle comes with two different structure. We use "would have" to describe some actions that we wanted to do in the past but couldn't do it due to some reasons. So, when it comes to reason, we have two structures to follow. First one is using 'but', and the other one is using past unreal condition (if) similar to third conditional. Similarly, "wouldn't have" is used to describe those actions that you didn't want to do, but you did it due to something else.

Would have using 'but': 

• I would have arrived on time for the meeting, but I lost the keys to my car. 
• I would have attended your marriage ceremony, but I was sick. 
• She would have invited you to her party, but she didn't know you were back from England. 

Would have using 'if':

• If you had informed me about your arrival, I would have waited for you at the airport. 
• She wouldn't have met an accident if she hadn't drunk so much at the party. 
• I would have never chosen this dress for my wedding if I had tried it before. 

Might + have 

Might have + past participle is used to guess/ speculate about something in the past that possibly happened, but we are not sure about it.  We can use “could have” too to give an opinion of something that may have occurred. 

Example: 

• Why was your friend absent yesterday? 

He might have been sick. 

He could have been sick.

• Why has tom not arrived yet?

He might have missed the bus

• Why wasn’t Brooklyn here yesterday?

She might have forgotten about the meeting. 

Conclusion: 

These all are the past modal verbs that are used to speculate about the past.  All of these four past modal verbs have different usage and meaning. Only “could have” and “might have” a bit similarity which is mentioned above.