A:Having tried; in doing
B:Tried; in being done
C:Having tried; to do
D:Tried; doing
下列各式,属于二元一次方程的个数有( )
①xy+2x﹣y=7;②4x+1=x﹣y;③ 1x +y=5;④x=y;⑤x2﹣y2=2
⑥6x﹣2y ⑦x+y+z=1 ⑧y(y﹣1)=2y2﹣y2+x.
美国的汽车城是:( )
“世上创痍,诗中圣哲;民间疾苦,笔底波澜。”这是郭沫若对哪位古代著名诗人的评价( )
用尖锐的东西挖耳屎容易导致耳聋,原因是( )