在Swing中，JButton的直接父类是（ ）。A． throws B． th

读短文，选答案。

   I'm Nancy. My birthday is August 15th. I usually get up early on my birthday because I am too excited

to sleep.  My parents. usually give me a birthday present. I don't go to school on my birthday, because it's

in summer holidays (假期). Usually I have a birthday party. We have a big dinner and eat a birthday cake. We also sing, dance and watch TV at the party. In the evening, my family goes out for a walk. I always

have a good time on my birthday.

1.  Nancy's birthday is in __________.

A. spring      

B. summer      

C. fall

2. Nancy usually gets up early on ________ .

A. Monday        

B. July 20th          

C. August 15th

3. Nancy usually _________ on her birthday.

A. goes to school  

B. has English class

C. has a birthday party

4. Nancy doesn't _________ at the party.

A. play sports      

B. watch TV      

C. dance

5. Nancy goes out for a walk with her _______.

A. family      

B. friends       

C. classmates

牛黄中胆红素的含量测定采用()

A．滴定法

B．分光光度法

C．薄层扫描法

D．气相色谱法

E．高效液相色谱法

按石灰中氧化镁含量可将其分为( )。

A．优等品、一等品与合格品

B．钙质熟石灰和钙质生石灰

C．镁质熟石灰和镁质生石灰

D．钙质生石灰和镁质生石灰

利用半导体二极管的（）导电特性，可组成整流电路。

A、双向

B、单向

C、脉动

D、全

HPLC，C₁₈色谱柱，0.5%乙酸铵-1%三乙胺-甲醇（49：1：50）为流动相，检测波长230nm，排列下列化合物保留时间由长到短的次序。