为什么要严格控制炉膛温度？

小明用31个等距离的结把一根绳子分成等长的30段，他一只手同时握住第1个结和第31个结，小红拉住第6个结，这时小东应该拉住第（　　）个结，拉紧绳子后才会得到一个直角三角形．

A．20

B．18

C．17

D．16

根据文章意思，首字母填空

Do you have any hobbies? If students don’t have any interest e___小题1:___ school work, they may become boring people. And that can influence their studies.

Studying without relaxing isn’t good for health. We can’t get good g___小题2:__ if we have bad health. We should do something we like. Some people like singing, taking photos and drawing p__小题3:__. Other people prefer collecting stamps, reading or shopping. I have a few hobbies, but my f___小题4:__ is collecting stamps. I like it best because I can learn a lot from stamps.

Some people collect stamps because they can m___小题5:__ money from the stamps. But I am just i___小题6:___ in collecting them and enjoy looking at them when I am free.

Stamp collecting is becoming more and more p___小题7:___ all over the world. I know an Australian boy and a French girl through the Internet. They both like collecting stamps. We show stamps to each other o___小题8:__. That is cool.

关于督脉，下列叙述不正确的是（）。

A.为"阳脉之海"

B.为"气血之海"

C.统率阳经

D.阳脉之都纲

E.督领全身之阳气

社区工作目标按照罗斯曼的分类，主要包括( )。

A．长期目标、短期目标、中期目标

B．社区目标、个人目标、组织目标

C．善用社区资源，满足社区需求

D．任务目标和过程目标

E．培养相互关怀和社区照顾的美德

研究经济问题时，一般要处理三种类型的数据：（）数据、（）和（）数据。