32. A. Their performance may improve. 　　B. Their immune system may be reinforced 　　C. Their blood pressure may rise all of a sudden. 　　D. Their physical development may be enhanced.

52. 　　What is crucial is recognizing that sustainable agriculture is not just about sustainable food production. 　　How do people ofen measure progress in agriculture? 　　(A) By its productivity (C) By its impact on the environmet 　　(B) By its sustainability (D) By its contribution to economic growth