分解因式：2a2-4a+2=______．
2a2-4a+2，
=2（a2-2a+1），
=2（a-1）2．
Were there sharks in the aquarium? [ ]
A. some
B. any
C. a lot
D. much
肠杆菌科细菌不具有的结构是（）
A.鞭毛
B.细胞壁
C.菌毛
D.荚膜
E.芽胞
