设8251A工作于异步方式，收发时钟频率为38.4KHz，波特率为2400。数据格式

根据上文内容判断正 (T) 误 (F)。

     Mrs Jones' telephone number is 2562781 and the number of the city cinema (市影院) is 2562718.

Because the two numbers look the same, some people often make a mistake (弄错) and telephone her

when they want the cinema.

     One evening, the Jones are having supper at the table. Just then, the telephone bell rings (铃响). Mrs

Jones goes to answer the telephone. A tired (累的) man says," Excuse me, at what time does your last

movie begin?"

     "I'm sorry," says Mrs Jones," But you have the wrong (错误的) number. This is not the cinema."

     "Oh, sorry, it began twenty minutes ago (以前)? Thank you all the same. Goodbye." Says the man.

     Mrs Jones is very surprised (惊讶), so she tells her husband (丈夫) the whole thing. Her husband,

Mr Jones laughs (笑) and says:" I see. The man's wife wants to go to a movie, but he is tired. He doesn't

want to go to a movie. So he telephones the cinema. His wife hears (听见) him, but she can't hear you.

Now they stay at home this evening, and the husband is very happy and he can have a good rest (休息)

at home."

( )1. Mrs Jones' telephone number is the same as the number of the city cinema.

( )2. People often telephone Mrs Jones when they want the cinema.              

( )3. One evening when the telephone bell rings, they are having supper.       

( )4. The tired man wants to know when the last film begins.                   

( )5. The husband is happy to stay at home.                                    

为了考察某校的教学水平，将抽查这个学校高三年级的部分学生本年度的考试成绩.为了全面反映实际情况，采取以下三种方式进行抽查（已知该校高三年级共有20个班，并且每个班内的学生已经按随机方式编好了学号，假定该校每班学生的人数相同）：①从高三年级20个班中任意抽取一个班，再从该班中任意抽取20名学生，考察他们的学习成绩；②每个班抽取1人，共计20人，考察这20名学生的成绩；③把学生按成绩分成优秀、良好、普通三个级别，从其中共抽取100名学生进行考察（已知该校高三学生共1 000人，若按成绩分，其中优秀生共150人，良好生共600人，普通生共250人）.

根据上面的叙述，试回答下列问题：

（1）上面三种抽取方式的总体、个体、样本分别是什么？每一种抽取方式抽取的样本中，样本容量分别是多少？

（2）上面三种抽取方式各自采用的是何种抽取样本的方法？

（3）试分别写出上面三种抽取方式各自抽取样本的步骤.

下列对保安员防火巡查的内容叙述错误的是（）。

A.消防设施、器材和消防安全标志是否在位、完整

B.安全出口、疏散通道是否畅通，安全疏散指示标志、应急照明是否完好

C.常闭式防火门是否处于关闭状态，防火卷帘下是否堆放物品影响使用

D.有消防设施、器材的部位是否有人员在位

经人民法院判决，建设单位应最迟于2009年4月5日向承包商支付工程款，但是届时却没有支付，则承包商请求强制执行的期限截止于( )。

A．2009年5月5日
B．2009年7月5日
C．2009年10月5日
D．2010年4月5日