Choose the correct words to fill in the blank.
To enforce discipline, the principal asked the teachers to _______ the strict vigilance to deter the habitual latecomers.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → keep up
Keep up means to continue something at the same level without letting it weaken. The principal wants the teachers to go on with their strict watch so that the habitual latecomers are deterred.
Complete sentence: To enforce discipline, the principal asked the teachers to keep up the strict vigilance to deter the habitual latecomers.
Example: The team must keep up the good work in the second half.
Why the Other Options are Incorrect?
Option 1: keep in — Incorrect. Keep in means to stop someone from going out, or to hold back a feeling; vigilance is not something to be held inside.
Example: The teacher kept the noisy boys in during the break.
Option 2: keep on — Incorrect. Keep on, in the sense to continue doing something, is followed by an -ing form ("keep on checking"), not by a noun such as vigilance.
Example: She kept on talking through the film.
Option 4: keep off — Incorrect. Keep off means to stay away from something or avoid it; it is the opposite of what the principal wants.
Example: Please keep off the grass.
Contrast: "keep up" is followed by a noun (keep up the vigilance), while "keep on" is followed by an -ing form (keep on checking).