阅读下面短文，掌握其大意，然后从每小题所给的A、B、C三个选项中，故答案选出一个最佳选项。
I have a good friend from Australia. Her name is Laura. Here is a photo of her family.
There is a nice girl and a1boy in the photo. The boy is her brother David. Laura is thirteen2, David is ten.3 do they look like? Laura is not fat and she is not thin4. She is of medium build. She has a round5like an apple. Her mouth is small, but her eyes are big. Her hair is6and blonde. Laura likes purple and she is often in purple clothes. She7being a singer. What about David? He is a little thin. David doesn't like8. His favorite color is green. David wants to be an actor. They like9movies very much. They often go to the cinema when they are free. It's relaxing for10to see a movie. You can also see a black dog in the photo. It's their pet dog Cici.
表示阿伏加德罗常数，则下列叙述正确的是
