根据中文意思选择英文句子。

1. 你好吗？ [ ]

A. How are you?

B. How old are you?

C. Who are you?

2. 关门。  [ ]

A. Open the door.

B. Open the pencil-case.

C. Close the door.

3. 数小棍。 [ ]

A. Count the sticks.

B. Count the books.

C. Count the squirrels.

4. 吃蛋糕。 [ ]

A. Eat a hamburger.

B. Eat a hot dog.

C. Eat a cake.

5. 再说一遍。 [ ]

A. Say it again.

B. Count it again.

C. Do it again.

影响电泳迁移率的因素有 （）

A.待分离生物大分子的性质

B.支持介质的筛孔

C.电渗

D.电场强度

E.粒子的净电荷缓冲液的性质