Question

Cyril, you really____
the principal's office while he was on holiday.
(oughtn't to be using,
oughtn't to have been using,
oughtn't have been using)​

Answer 1

$\huge \mathbb\fcolorbox{black}{peachpuff}{Answer}$

oughtn't have been using

Answer 2

Cyril, you really oughtn't to have been using the principal's office while he was on holiday.

The word 'ought' is a verb.

1. The verb can be defined as any form of action that is done by a being. For example, sleeping, yawning, breathing, and so on. Even in simple tasks like watching a Tv, the word 'watching' is a verb.
2. Also, the sentence is negative. We understand that due to the "n't" at the end of the word. A sentence is deemed to be negative when it does not affirm anything and has words like no, not, never, and so on.
3. Words like can't, haven't, don't, hasn't, and so on also change a sentence to negative.

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