阅读短文，补全下列句子(每空一词)。

     Lily is from New York , the U.S.A. She is twelve. She is in Shanghai NO.3 Junior High School. She

is in Class Eight, Grade One. Her phone number is 66786019. Dongdong is from Kunming. His English

name is Tom. He is eleven .He is in Class Seven,Grade One. His telephone number is 24524233. They

are not in the same class. They are good friends.

1. Lily is in No. _____ Junior High School.

2. Dongdong is in Class  _____ .

3. Lily and Dongdong are good _____.  

4. Tom is from _____.

5. Lily is _____ years old.

下列表达式中，I表示电流，U表示电压，R表示电阻，E表示电源电动势，r表示电源内阻，则闭合电路欧姆定律表达式应为（）。

A.A

B.B

C.C

D.D