The invigilator … to know how long the examination … going on.

Step 1: Analyze the question The sentence is in reported (indirect) speech: "The invigilator _ to know how long the examination _ going on." We need the right tense for each gap.

Step 2: The concept When the reporting verb is in the past tense (e.g., wanted), the verb in the reported clause shifts back one tense. The present perfect continuous ("has been going on") becomes the past perfect continuous ("had been going on").

Direct speech: "How long has the examination been going on?" Reported speech: The invigilator wanted to know how long the examination had been going on.

Step 3: Check the options

• A. wanted / had been: the past tense matches the past perfect, and the sentence is grammatically correct.
• B. wanted / has been: the tenses are not consistent. A past reporting verb should not be followed by "has been".
• C. want / had been: "want" does not agree with the singular subject "invigilator". It should be "wants", and it also clashes with "had been".
• D. wanted / have been: "have been" does not agree with the singular subject "examination".

Step 4: Answer The correct option is A: The invigilator wanted to know how long the examination had been going on.

Tip: In reported speech, if the first verb is in the past tense, push the verb in the second clause one step back in time:

• has/have been → had been
• is → was
• will → would

This works for most JAMB and WASSCE "sequence of tenses" questions.