Modal Auxiliary Verbs - Could

Definition

The modal verb could is most often used as a past-tense version of can, indicating what someone or something was able to do in the past; it can also be used instead of can as a more polite way of making a request or asking for permission. Could is also used to express a slight or uncertain possibility, as well as to make a suggestion or offer.

Past ability

When describing what a person or thing was physically, mentally, or functionally able to do in the past, we use could instead of can. For example:
  • “When I was younger, I could run for 10 miles without breaking a sweat!”
  • “Back in the 1970s, our TV could only get about four channels.”
  • “She couldn’t read until she was nearly 12 years old.”
  • Could your family afford any food during the Great Depression, Grandma?”
We also use could instead of can when describing an ability that is desired or wished for. (This is known as the subjunctive mood, which is used for describing hypothetical or unreal situations.) For example:
  • “I wish I could swim; it looks like so much fun.”

Conditional sentences

Conditional sentences in the past tense are called second conditionals. Unlike the first conditional, we use the second conditional to talk about things that cannot or are unlikely to actually happen.
To create the second conditional, we usually use the past simple tense after the if clause, followed by would + a bare infinitive to describe what would be the expected (if unreal) result of the condition.
However, if we want to describe what we would be able to do under a certain condition, we can use could instead. For example:
  • “If I got that promotion at work, I could finally afford a new car!”
  • “If we moved to California, I could surf every day!”
We often use could in what’s known as a mixed conditional, which occurs when the tense in one part of a conditional sentence does not match the other half. This often occurs with could when a present-tense verb is being used in an if conditional clause to express a hypothetical scenario that is likely to or possibly could happen. For example:
  • “If I get some money from my parents, we could go to the movies.”
  • “We could visit our friends at the beach if you ask your boss for Friday off.”

Asking for permission

When we ask someone for permission to do something, it is often considered more polite to use could instead of can. However, we can only make this substitution when asking for permission—when stating or granting permission, we can only use can (or, more politely, may).
For example:
  • “Dad, could I spend the night at my friend’s house?”
  • Could we invite Sarah to come with us?”
  • “I was wondering if I could take a bit of time off work.”

Making a request

Just as we use could instead of can to be more polite when asking for permission, it is also considered more polite to substitute could when making a general request. For example:
  • Could you please be quiet?”
  • Could you help me with this assignment?”
Note that we can also do this with the modal verb would:
  • Would you ask Jeff to come over here?”
  • Would Tina help me paint this fence?”

As a rhetorical device

Sometimes, we use could as a rhetorical device to politely introduce or emphasize an opinion or sentiment about something, in which case we invert could with the subject. For instance:
  • Could I just say, this has been a most wonderful evening.”
  • “And could I clarify that I have always acted solely with the company’s interests in mind.”
  • Could I add that your time with us has been greatly appreciated.”
Note that we can accomplish the same thing by using the verbs let or allow instead, as in:
  • Let me clarify: this decision is in no way a reflection on the quality of your work.”
  • Allow me to add, we were greatly impressed by your performance.”

Possibility and likelihood

Like can, we can also use could to describe actions or outcomes that are possible or likely. Unlike using could to talk about an ability, this usage is not restricted to the past tense. For instance:
  • “I think it could rain any minute.”
  • “She could be in big trouble over this.”
  • “Due to this news, the company could see a sharp drop in profits next quarter.”
  • “Be careful, you could hurt someone with that thing!”
  • “Answer the phone! It could be your father calling.”

Making a suggestion

Similar to expressing a possible outcome, we can also use could to suggest a possible course of action. For instance:
  • “We could go out for pizza after work on Friday.”
  • “You could see if your boss would let you extend your vacation.”
  • “I know it will be tricky to convince your parents, but you could try.”

Adding angry emphasis

We also use could to add emphasis to an angry or frustrated remark. For example:
  • “My mother has traveled a long way to be here—you could try to look a little more pleased to see her!”
  • “You could have told me that you didn’t want a party before I spent all this time and effort organizing one!”

Making offers

In addition to using could to make a suggestion, we can also use it to make an offer to do something for someone. For example:
  • Could I give you a hand with dinner?”
  • Could we help you find what you need?”
  • Could I give you a ride home?”

Rhetorical questions

Could is sometimes used informally in sarcastic or rhetorical questions that highlight a behavior someone finds irritating, unacceptable, or inappropriate. It is often (but not always) used with be as a main verb. For example:
  • Could you be any louder? I can barely hear myself think!”
  • “Oh my God, Dad, could you be any more embarrassing?”
  • “Danny, we’re going to be late! Could you walk any slower?”
Quiz

1. Which of the following is not a function of the modal verb could?





2. Which of the following sentences uses could to express possibility or likelihood?





3. Which of the following sentences uses could incorrectly?





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