What is crucial is recognizing that sustainable agriculture is not just about sustainable food production.

　　52. How do people often measure progress in agriculture?

　　A) By its productivity

　　B) By its sustainability

　　C) By its impact on the environment

　　D) By its contribution to economic growth

　　53. Specialisation and the effort to increase yields have resulted in________.

　　A) localised pollution

　　B) the shrinking of farmland

　　C) competition from overseas

　　D) the decrease of biodiversity

　　54. What does the author think of traditional farming practices?

　　A) They have remained the same over the centuries

　　B) They have not kept pace with population growth

　　C) They are not necessarily sustainable

　　D) They are environmentally friendly

　　55. What will agriculture be like in the 21st century?

　　A) It will go through radical changes

　　B) It will supply more animal products

　　C) It will abandon traditional farming practices

　　D) It will cause zero damage to the environment

　　56 What is the author’s purpose in writing this passage?

　　A) To remind people of the need of sustainable development

　　B) To suggest ways of ensuring sustainable food production

　　C) To advance new criteria for measuring farming progress

　　D) To urge people to rethink what sustainable agriculture is