分解因式a-ab2的结果是[ ]
A.a(1+b)(1-b)
B.a(1+b)2
C.a(1-b)2
D.(1-b)(1+b)
答案:A
给下列句子排序。
( ) Did you read books?
( 1 ) What did you do yesterday?
( ) Did you clean your room?
( ) I went to the park.
( ) No, I didn't clean my room.
( 6 ) Yes, I read some books.
引起成年人急性黄疸型肝炎最主要的病原为
A.HAV
B.HBV
C.HCV
D.HDV
E.HEV