I know for a fact that for some verbs like 'say', 'indicate', 'know', 'claim', the deletion of 'that' is usually optional, though it's safer to include it. However, does the same apply when 'that' is used to linked a subject to a independent clause?

To clarify with an example:

  • The worst thing is you don't even know who did it.


  • The worst thing is THAT you don't even know who did it.

Which one is grammatically correct, if not both?

Note: I am having trouble finding something to refer to that specifically discusses the omitting of 'that' after verb-to-be. Providing me with a link would be greatly appreciated.

Many thanks in advance.

  • 2
    Although the same rules of English grammar apply to both written and spoken English, often spoken English is used in a more casual and sloppy way (i.e. not in a perfectly grammatical manor). Both example sentences you provide would be acceptable when used as spoken English, but your second example sentence (the one with the word "that") is more grammatically correct and should be used in written English. Commented Mar 10, 2017 at 12:29
  • 1
    @JavaLatte: Sorry, I misspelled; it should have used 'manner' and not 'manor'. It could be reworded to say "not in a perfectly grammatical style (way of doing something' with close to the same meaning. Commented Mar 10, 2017 at 12:38
  • 2
    That's a very good question, JUCINATOR. It's certainly true that that can be omitted when it's after a that-clause verb (after say, know, think etc) but I can't find be in any such list. My feeling is that omission is not as comfortable as for a bona fide that-clause verb, where you know that there should be a that there, and can mentally pencil it in if it's omitted.
    – JavaLatte
    Commented Mar 10, 2017 at 12:41

1 Answer 1


"The worst thing is" is already a fairly informal utterance, and you will find many examples of The worst thing is, you... and The worst thing is, they...

If you're concerned about striking a formal tone, the worst thing you could do is use the phrase the worst thing is, with or without that.

  • What I take from reading your answer is that even in informal situations, I must include a comma between verb to be and the noun that directly follows it. Is this true?
    Commented Mar 14, 2017 at 12:36
  • By reflecting the syntactic micro-pause that would naturally occur between the two clauses in speech, the comma guides the reader parsing the sentence. There is no "must" in such matters. It is simply a reasonable thing to do.
    – TimR
    Commented Mar 14, 2017 at 13:39

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