Nowadays, people in my village use a combine harvester to D. harvest their rice.

• Explanation: A combine harvester is specifically used to harvest crops.

Ba works B. more lazily so he often gets worse marks than Tuan.

• Explanation: "More lazily" is the correct comparative form of the adverb.

In his free time, my younger brother is keen on B. doing puzzles and taking photos.

• Explanation: "Doing puzzles" is the correct phrase to use in this context.

Farmers now use different farming methods to A. increase their production.

• Explanation: "Boost" means to increase, so "increase" is the closest synonym.

My brother likes playing badminton with his friends in his B. leisure time.

• Explanation: "Free time" is synonymous with "leisure time."