Sorry if this question is too simple. Someone wrote a sentence in which he used the word "alacrity" and asked whether he used it correctly. A native speaker replied:
I have a feeling many people could not define alacrity.
Does "could not" sound natural here?
I know that "could" can be used when we are not completely certain about something or to talk about a future possibility but isn’t "could" in "people could not define" referring only to the past?
I would expect "people would not be able to define".
"Could" like many basic words, has a wide range of meaning.
I suspect that many people could not [do] X.
pretty much means
I suspect that many people are not able to [do] X.
This is distinct from the senses of "could" referring to future possibility.
- A human could not live for more than a few minutes in a vacuum.
- A normal ten-year-old could easily understand thsi concept.
- An adult elephant could easily pull a two-ton load.
- A writer could include both first-person and third-person sections in a novel.
- An airplane could not function where the air is too thin.