Q. Complete the sentence with proper preposition. We usually finish work early ________ Fridays.

Explanation:

Use ‘on’ before days and dates. ‘On Fridays’ means every Friday (a habitual action). The other options are incorrect here: ‘at’ is for specific times or set phrases (at 5 pm, at night), ‘in’ is for longer periods (in June, in 2025, in the morning), and ‘during’ is used for events/periods (during the meeting), not specific days of the week.