A:none of them were here
B:no one was here
C:all of them were here
D:all of them were not here
分解因式:x2-2xy+y2+x-y=____
以下能正确反映酵母菌发酵时,产酒量随温度变化的曲线是( )
下列各组词语中,错别字最多的一项是 ( )