NDA (I) 2017 General Ability Test · Question 24 of 149

Correct — B, have told. The tag 'but he did' shows the telling actually happened in the past, and a past act that ought not to have occurred is expressed by 'ought not to have' plus the past participle — 'He ought not to have told me your secret, but he did.'

• (a)telling — 'Ought to' is followed by a plain infinitive, never by an -ing form, so 'ought not to telling' is not possible.
• (c)having told — A perfect -ing form cannot follow the 'to' of 'ought to'; the perfect after this modal is built with 'have' plus the past participle.
• (d)No improvement — The plain infinitive 'tell' points to the present or future, which contradicts 'but he did' and leaves the sentence describing an act that has not yet happened.

A modal-perfect item — 'ought not to have + past participle' criticises something that was in fact done.

• 'Ought to have', 'should have', 'could have', 'needn't have' and 'must have' all describe past time.
• The plain form after these modals refers to present or future time instead.

• Ignoring the short clause at the end of the sentence, which is what fixes the time frame.

Asked as a sentence-improvement item where a trailing clause reveals that the modal must refer to past time.

No directly related past PYQ was found.

• practice — not a real PYQ

  Which option best improves the underlined part — You should <u>inform</u> me earlier, but you did not.

  • (a)have informed
  • (b)informing
  • (c)having informed
  • (d)No improvement

  Answer(a) have informed — a past obligation that was not met takes 'should have + past participle'.

• practice — not a real PYQ

  Which option best improves the underlined part — He needn't <u>come</u> yesterday, as the meeting had been cancelled.

  • (a)have come
  • (b)coming
  • (c)came
  • (d)No improvement

  Answer(a) have come — 'needn't have come' describes an unnecessary past action.