Choose the sentence in which the modal has been used incorrectly:

The correct answer is Option (4) → If I were the class monitor, I will keep the classroom windows open all day.

Would in the second conditional:

• The given sentence says “If I were the class monitor, I will keep”.
• “If I were” talks about an imagined situation. The speaker is not the monitor.
• In such a sentence, the other part takes would + base verb (the simple form of the verb, like go, eat), not “will”.
• Corrected: If I were the class monitor, I would keep the classroom windows open all day.

Why the Other Options are Incorrect?

Option 1: Need I bring my own racket to the badminton camp? This sentence is correct. “Need” works as a modal in a question, so it takes the base verb “bring” with no “to”.

Option 2: You had better leave now if you want to catch the last metro. This sentence is correct. “Had better” gives strong advice and takes the base verb “leave” with no “to”.

Option 3: The new boy dare not argue with the umpire. This sentence is correct. “Dare not” is a modal here, so it takes no -s and is followed by the base verb “argue”.