根据下面所提供的对话情景，在每个空白处填入一个适当句子，使其意义连贯、完整。

A: Look at this photo of my family. This is my father and this is my mother.

B: (1)__________________________

A: It's my little brother.

B: He looks very clever.(2) ______________________________

A: He is six years old. Look! He is riding a bike.

B: Could you ride a bike when you were six?

A: No, I couldn't.(3)________________________________

B: I could when I was six. And I rode well.

A: By the way. (4)________________________________

B: No, thanks. I'm not thirsty.A:What about some moon-cakes?

B: (5)_________________________ Oh, they are delicious. Thank you.

下面有关疫点、疫区、受威胁区的说法正确的是（）。

A.疫点：指患病动物所在的地点。一般是指患病禽类所在的禽场（户）或其它有关屠宰、经营单位；如为农村散养，应将自然村划为疫点。

B.疫区：由疫点边缘向外延伸3公里的区域划为疫区。疫区划分时，应注意考虑当地的饲养环境和天然屏障（如河流、山脉等）。

C.受威胁区：由疫区边缘向外延伸5公里的区域划为受威胁区。

D.由所在地县级以上兽医行政管理部门划定疫点、疫区、受威胁区。