Choose the correct prepositions for the blanks : He has been living ........... Calcutta ........... last three years.

Right Answer: in, for

Two blanks need two different prepositions here. 'Live in' is used with a city or a town, so the first blank takes 'in Calcutta'. The second blank follows the present perfect continuous tense 'has been living', which needs a period of time. 'For' is used with a duration such as three years, three hours or a long time, whereas 'since' is used with a fixed point of time such as 2019 or Monday. 'Last three years' shows duration, not a starting point, so 'for' is correct. Hence the right answer is 'in, for'.