x2y2(x+y)-8xy(x+y)+16(x+y)
=(x+y)(x2y2-8xy+16)
=(x+y)(xy-4)2.
防止下颌侧方脱位的是()
A.颞下颌韧带
B.蝶下颌韧带
C.关节囊
D.茎突下颌韧带
E.盘-锤韧带