A:bought, didn't read
B:bought, haven't read
C:have bought, didn't read
D:have bought, haven't read
根据家兔和狼的牙齿图解,回答有关问题:
二次函数y=x2-6x+5的图像的顶点坐标是( )
回顾历史,我们这艘“中国号”巨轮之所以能经受住一次又一次的严峻考验,取得一个又一个的辉煌成绩,归结起来就是 ()