问题 单项选择题

某CPU的主振频率为100 MHz,平均每个机器周期包含4个主振周期。各类指令的平均机器周期数和使用频度如表2.9所示,则该计算机系统的速度为平均约 (8) 兆指令/秒。若某项事务处理工作所要执行的机器指令数是控制程序(以访内、比较与转移等其他指令为主)220000条指令和业务程序(以包括乘除在内的算术逻辑运算为主)90000条指令,且指令使用频度基本如表2.9所示,则该计算机系统的事务处理能力约为 (9) 项/秒。若其他条件不变,仅提高主振频率至150 MHz,则此时该计算机速度为平均约 (10) 兆指令/秒,对上述事务的处理能力约为 (11) 项/秒。若主频仍为100 MHz,但由于采用了流水线和专用硬件等措施,使各类指令的每条指令平均机器周期数都变为1.25,则此时计算机的速度平均约 (12) 兆指令/秒。
表2.9 各类指令的平均机器周期数和使用频度

指令类别平均机器周期数/指令使用频度
访内存2.525%
一般算术逻辑运算1.2540%
比较与转移等1.525%
乘除155%
其他55%

A.1
B.5
C.10
D.15
E.20
F.33.3
G.50
H.66.7
I.100
J.200

答案

参考答案:D

阅读理解

阅读理解。

     任务型读写。请认真阅读下面短文,并根据所读内容在文章后图表中的空格里填

入最恰当的单词。)注意:每空不超过1个单词。

     Maybe you are an average student. You probably think you will never be a top student.

This is not necessary so, however. Anyone can become a better student if he or she wants to.

Here's how:

     1. Plan your time carefully. When you plan your week, you should make a list of things

that you have to do. After making this list, you should make a schedule of your time. First your

time for eating, sleeping, dressing, etc. then decide a good, regular time for studying. Don't forget

to set aside enough time for entertainment. A weekly schedule may not solve all your problems,

but it will force you to realize wha is happening to your time.

     2. Find a good place to study. Look around the house for a good study area. Keep this

space, which may be a desk or simply a corner of your room, free of everything but study materials.

No games, radios, or television! When you sit down to study, concentrate on the subject.

     3. Make good use of your time in class. Take advantage of class time to listen to everything

the teachers say. Really listening in class means less work later. Taking notes will help you remember

what the teacher says.

     4. Study regularly. When you get home from school, go over your notes. Review the important

points that your teacher mentioned in class. If you know what your teacher is going to discuss the

next day, reading that material will become more meaningful, and you will remember it longer.

     5. Develop a good attitude about tests. The purpose of a test is to show what you have

learned about a subject. They help you remember your new knowledge. The world won't end if

you don't pass a test, so don't be overly worried.

     There are other methods that might help you with your studying. You will probably discover

many others after you have tried these.

                                              How to become a better student

单项选择题