1. What do you usually do on weekends?

2. What do you usually do at weekends?
3. What do you usually do in weekends?

Which one is correct? Can we use all prepositions?

Only the first one is correct.

=)

All three questions are grammatically correct, but they have slight differences in terms of usage.

1. "What do you usually do on weekends?" - This is the most common and widely accepted form of phrasing the question. "On" is the most commonly used preposition when referring to specific days or time periods, such as weekends, weekdays, or specific dates.

2. "What do you usually do at weekends?" - While less common, using "at" instead of "on" is also grammatically correct and widely used in some English-speaking regions, particularly in British English. This form emphasizes the idea of being present during the entire weekend duration.

3. "What do you usually do in weekends?" - Though this is grammatically correct, it is less commonly used than the previous two forms. "In" is generally used when referring to a period of time in a more abstract or general sense, such as in the phrase "in the morning" or "in the evening."

In summary, both "on" and "at" can be used interchangeably to refer to weekends, while "in" is less commonly used in this context. The choice of preposition may vary depending on regional or personal preferences.