阅读理解。

     Come and look at the photo. It's an American family. The woman in the middle is Beth White. She is our

teacher. The old woman on her right is her mother. She is Mrs. White. The man on her left is her father, Mr

White. He is an artist. The other young woman is Doris White. She is her sister. Doris White has two children.

They are students. Leo Bush is her son and May Bush is her daughter. May sits between her grandfather and

her father.  

     "What are they doing?"

     "The family are having a big dinner on Thanksgiving Day (感恩节)."

1. This is _______ family photo.

A. an American

B. an English

C. a Chinese

2. There are _______ in Beth White's family.

A. six people

B. seven people

C. five people

3. They are having _______.

A. sports

B. a family meeting

C. a big dinner on Thanksgiving Day

4. Beth's family name is _______.

A. Smith

B. White

C. Bush

5. Leo and May's father is _______.

A. Mr White

B. Mr Smith

C. Mr Bush

将50364四舍五入并保留两个有效数字是（    ）。