Industrial production of powders involves mechanical forces fracturing individual particles of material into ever-smaller particles. The theory explaining this fracturing recognizes two general types of behavior exhibited by material under stress: elastic and plastic deformation. Elastic deformation occurs when stress is placed or a brittle material, which deforms and then returns to its original shape when stress is removed. If the material is stressed too heavily, however, excess energy builds up and the material fractures. This behavior makes brittle material fracture suddenly when subjected to mechanical impact by powder-making machines. No brittle, or ductile, materials by contrast, are harder to fracture, since they respond to comparable amounts of stress by deforming plastically, that is, by changing sh ape permanently. Excess energy that builds up in the strained material is expended in deformation of the material rather than in fracturing. Plastic behavior can al so be exhibited by brittle materials as their particles become smaller during processing and thus less susceptible to fracturing.

　　反義詞

　　28. DISAVOW

　　A. instigate B. acknowledge C. envision D. ameliorate E. inculcate

　　29. FLOURISH

　　A. lose out B. catch up C. turn off D. waste away E. slow down

　　30. HYPERBOLE

　　A. misdemeanor B. understatement C. imprecation D. concession E. obstinacy

　　31. RIVETING

　　A. appetizing B. enriching C. wearisome D. wasteful E. harmful

　　32. DAMN

　　A. undo B. entreat C. mollify D. motivate E. extol

　　33. REPROACH

　　A. sustain B. advance C. acclaim D. manipulate E. embellish

　　34. MYOPIA

　　A. maturity B. prescience C. prompt response D. good fortune E. final event

　　35. NICE

　　A. restrained B. colorless C. obscure D. imprecise E. balanced

　　36. LASSITUDE

　　A. pride B. breadth C. vim D. pomp E. valor

　　37. PUSILLANIMOUS

　　A. successful B. sociable C. adept D. stouthearted E. trustworthy

　　38. ABASE

　　A. aggrandize B. limit C. defy D. purify E. destabilize

　　參考答案：

　　BDBC ECBD CDA