can, may

When you see can in your writing, consider deleting it. Can implies ability but not action. Rewrite to describe the action if possible.

Use the /b option to force a black-and-white screen.

When ability is what you need to express, it's OK to use can to describe actions or tasks that the reader or program is able to do. Use might to express possibility. Don't use may, which might be interpreted as providing permission.

Don't substitute could for can unless you're referring to the past.