在Rt△ABC中，∠C=90°，AC=9，BC=12，则其外接圆的半径为____

阅读短文，判断正（T）误（F）。

                                                              The Soap Opera

     Many people like to watch TV. There are all kinds of programs on TV. The soap opera is one of them.

     The soap opera was first on the radio in the 1920s. Then it started on TV in the 1940s. 

     Why do so many people like to watch soap operas on TV, especially young people? What makes soap

operas popular? Let's find out.

      First, what's happening in the soap opera is very different from our lives. Everything is perfect (完美的)

in the play. People don't need to worry about almost anything. People don't have money problems.

      Second, there are many beautiful girls and handsome (英俊的) boys in the soap opera. They are so cool.

They drive young people crazy (疯狂的). They make young people happy. 

     Third, the story in the soap opera is usually interesting. It makes people relax after a day's hard work. Even

some old people like to watch it, too. But some people don't like it. They think the show is too slow and too

long. Do you like watching soap operas? What do you think of them?

( )1. The soap opera started on TV  in the 1920s.                                    

( )2. What's happening in the soap opera is very different from our lives.           

( )3. The beautiful girls and handsome boys in the soap opera make young people crazy.

( )4. People like soap operas because they can make people relax.                    

( )5. All people like soap operas.                                                   

属于严格管理的传染病是（）

A.艾滋病

B.鼠疫

C.血吸虫病

D.流行性感冒

E.麻风病

液一液萃取分离法中，分配比是指溶质在有机相中的总浓度和溶质在水相中的总浓度之比。( )

通过毕业答辩而未建议授予学位者，经论文答辩委员会全体成员半数以上同意，并做出决议，可在（）内修改论文，重新申请学位答辩一次。

A.三个月

B.半年

C.学习年限内

什么叫内丹？什么叫外丹？有什么区别？