彤彤做错了下列计算题中的一道题,你认为她做错的题是( )
A:yx2÷-y2x=1xy
B:3x-2y2·2x-3x3=-2y3x
C:xyx2-2xy+y2÷xy2+x2yx2-y2=1x-y
D:x2+xx2+2x+1·x2-1x-1=xx+1
下列句子中,划线的成语使用恰当的一项是 ( )
Large amounts of food ______ wasted in our school everyday, but the poor in many countries ______ no access to drinking water.
下列有关唐对外交往的正确叙述是( )