i know wh words can be used in wh clauses apart from wh questions, so i have one doubt below, which is mentioned below. please let me know which is correct or both correct?

  1. we should know, what they eat and what they do not.
  2. we should know, what do they eat and what do not.

any other usage of Wh words exaplanation is appreciated

  • What do you mean by wh clauses? Can you please expand this abbreviation? There are some abbreviations (such as "sth" and "s.o.") which are used in some textbooks but which are not preferred on ELL Stack Exchange, so that the site is easy to read by everyone. Thank you! Keep contributing! Jul 15, 2019 at 10:54

2 Answers 2


"What" in your sentences is not used to form a question. So, sentence 2 is incorrect.

Sentence 1 can be re-written as:

We should know what they eat and do not (eat).


I'm unclear what you mean by wh words. Do you mean question words (what, where, when, why)?

As for you your sentences, the second one is ungrammatical (and wrong-sounding) because the what do not at the end requires a subject. I should be what they do not as in your first sentence.

In both cases, you should remove the comma since the "we should know" is not a separate clause:

We should know what they eat and what they do not

We should know what they do and do not eat

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