có mấy cách chuyển đổi câu CĐ thành câu BĐ ? vd cho mỗi cách chuyển đổi

Câu IV (1,0 điểm): Chọn 1 từ thích hợp trong bảng để điền vào mỗi chỗ trống của đoạn văn dưới đây.
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Many tourists like to send postcards to their friends and family. They send them when they are (1)..... on holiday. These postcards often have pictures on one side and a message (2)...... can be written on the other. The pictures on them are better (3)...... than the photos they take. The first postcards were sent at the end of the nineteenth century. There was a picture of a town on them. Later on, they had pictures showing important events. People liked to see them because there were not (4)..... any pictures in the newspapers then.

phương pháp lập luận của văn nghị luận?