“Does she want to see Gatsby?”
“She’s not to know about it. Gatsby doesn’t want her to know. You’re just supposed to invite her to tea.”

As far as I know, the usual way to build a negative sentence in English is to use do/does not, so I was surprised to see such a sentence.

Why don't "She doesn't know about it."? When should we use the "be not to" construction?

  • 1
    It's a negation of the BE to VERB construction, which has future reference, not present, and is in the deontic mode (relating to what is expected or obligatory). She is to know about it means, approximately, "She is expected to learn about it, she should be told, someone should inform her", so She is not to know about it means, approximately, "She should not learn about it, she should not be informed". – StoneyB on hiatus Jun 8 '15 at 14:25

Contemporary American English usage includes a participle to convey this idea.  Possible options include: 

  • She is not supposed to know about it.
  • She is not allowed to know about it.
  • She is not intended to know about it.

The same idea can be expressed with a modal auxiliary:

  • She cannot know about it.
  • She should not know about it.
  • She must not know about it.

This is a different idea than the one expressed by "She does not know about it".  Since it's followed by "Gatsby doesn't want her to know," I take it to mean something like "She doesn't have permission to know about it.  Gatsby is withholding permission."  The implication of the overall passage is "You don't have permission to tell her."

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.