72. A 主旨大意题。由文章的第一段最后一句可得出文章的中心内容。

73. D 代词指代题。根据文章第三段中的“So they educated the poor people in the city to compost this waste.”可知“them”指代“the poor people in Dhaka”。

74. C 细节理解题。根据文章第二段中的“Drayton believes that anyone can become an agent for change...it is many young people's ambition to set up programmes or businesses that improve social conditions.”可知，只要年轻人努力提高社会状况，就能成为一个改变者。

75. D 观点态度题。根据文章最后一段内容可知作者对“Ashoka's program”持积极态度。