Choose the most suitable option to replace the highlighted part of the sentence: She do not knows the answer to this question.

Correct — B. The trigger is the subject She — third person singular.

In a simple-present negative, the auxiliary carries the agreement and the main verb stays bare: does + not + know.

The printed 'do not knows' does the reverse — do, the form for I, you, we and they, with an -s on the main verb. She does not know the answer → option (b).

Why the others are wrong

• (a)
  do not knew — Two faults: the auxiliary do clashes with she, and after do, does or did the main verb takes its base form — never the past form knew.
• (c)
  is not knowing — Know is a state verb — a condition, not an action in progress — so it is not normally used in the continuous. She does not know, not she is not knowing.
• (d)
  do not know — The main verb is now right, but the auxiliary is not: with a third-person singular subject like she, do must become does.

English builds simple-present negatives and questions with the auxiliary do. The auxiliary takes the agreement: does with he, she, it or a singular noun, and do with I, you, we, they and plurals.

The -s marks the verb phrase only once. Once does carries it, the main verb returns to its base form: she knows → she does not know.

Key facts

• Simple-present negatives take does not with he, she and it, and do not with I, you, we and they.
• After any form of do — do, does, did — the main verb takes its base form.
• State verbs such as know, believe and understand are not normally used in continuous tenses.

Common traps

• Picking 'do not know' because know now looks right — the auxiliary still disagrees with she.
• Keeping the -s on both words — 'does not knows' marks the person twice.

No directly related past PYQ was found.