—Look, she ____ (talk) with her students over there.
下列选项中,属于相对性状的是( )
先化简,再求值:
2x2+3(﹣x2+3xy﹣y2)﹣(﹣x2﹣2y2),其中x= 12 ,y=﹣2.
经过科学家的不懈努力,逐渐建立了遗传学。下列有关叙述错误的是( )