The plane will arrive in Haikou in half ______ hour.

   A hobby is a special interest or an activity that people like to do in their free time．Most people in Britain have their own____(hobby)．

   Some people train dogs to race or keep pigeons(鸽子)____(carry)messages．Some people are crazy about plants．They put many  ____(kind)of beautiful flowers in their kitchens and living rooms．____(other)are mad about their cars or motorbikes．They spend their weekends____(wash)them，painting them and trying 

____(make)them go faster．Children and teenagers are  ____(interest)in collecting things．They collect stamps，postcards or pictures of a favourite pop star．

   ____(learn)something new is also people's hobby．Some people go to evening classes to learn  ____(dance)，body building，bread making and so on．Some people learn these things by ____(they)．

以下是人体部分生理活动示意图，请据图回答：

（1）血管①②③④中流动脉血的是　____ 

（2）图中所示与外界相连的4条途径中，过程“4”叫做____ 

（3）人体摄入的蛋白质分解成____ 后，才能通过小肠的a过程进入血液运往全身．

（4）每个肾脏中大约有100万个肾单位，在肾单位中有____ 处毛细血管，请列举一处毛细血管的作用____ 

在历史学习中，我们经常会碰到“历史现象”与“历史结论”的区别问题。历史结论是在对历史现象的理性认识和基本判断基础上形成的结论。下列属于历史结论的是（   ）