A:顶细胞
B:泡状细胞
C:基细胞
D:胚柄细胞
It seems that the old man for something over there.
抛掷两枚质地均匀的硬币,两枚硬币落地后,正面都朝上的概率是
已知,△ABC∽△DEF,△ABC与△DEF的面积之比为1:2,当BC=1,对应边EF的长是( )