TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The crosslinking agent in the right-and-left region is peroxy ketal compound having half-life of 1 hour at 110-120 degrees C or peroxy carbonate compound having half life of 1 hour at 90-130 degrees C. The crosslinking agent in middle region is dialkyl peroxide having half life of 1 hour at 130-150 degrees C and peroxy carbonate having half life of 1 hour at 110-130 degrees C. The content of crosslinking agent in right-and-left region and middle region with respect to 100 parts weight of ethylene vinyl acetate copolymer is 1.6-3 parts weight and 0.1-1.5 parts weight, respectively. The crosslinking adjuvant is chosen from triallyl isocyanurate, triaryl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, ethylene glycol diacrylate, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. The ultraviolet ray absorber is chosen from 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxy benzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxy benzophenone, 2-hydroxy-4-n-octadecyloxy benzophenone, 2-hydroxy-4-benzyloxy benzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2',4,4'-tetrahydroxybenzophenone. The ultraviolet stabilizer is chosen from bis-2,2,6,6,-tetramethyl-4-piperidinyl sebacate, bis-1-methyl-2,2,6,6-tetramethyl-4-piperidinyl sebacate, bis-1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl sebacate, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazol, 2-(2-hydroxy-3,5'-di-tert-amyl phenyl)-2H-benzotriazole and polymethyl propyl-3-oxo-4-(2,2,6,6-tetramethyl-4-piperidinyl) siloxane. The silane coupling agent is chosen from gamma -methacryloxypropyl trimethoxysilane, N-( beta -aminoethyl)- gamma -aminopropyltrimethoxysilane, N-( beta -amino ethyl)- gamma -aminopropyl methyldimethoxysilane, gamma -aminopropyl triethoxysilane and gamma -glycidoxypropyl trimethoxysilane.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The sheet further comprises crosslinking adjuvant, ultraviolet absorber, ultraviolet stabilizer and silane coupling agent.