计算:[x(xy2+2xy)-y(x2y-6x2y2)]÷2x2y.
原式=(x2y2+2x2y-x2y2+6x2y3)÷2x2y=(2x2y+6x2y3)÷2x2y=1+3y2.
Only in recent years ______ begun to realize that wild dogs, kept within bounds, often do more good than harm.
A.people have
B.since people have
C.have people
D.people who have
滑膜性软骨化生的临床表现包括()
A.关节长期不适,运动逐渐受限
B.局部出现疼痛、肿胀
C.偶尔关节活动时有捻发音或关节交锁
D.大关节滑膜内有多发性软骨结节,也可发生在滑囊或腱鞘
E.关节本身亦有关节炎症