某CPU的主振频率为100MHz,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3-1所示,则该计算机系统的速度为平均约 (5) 兆条指令/秒。 表3-1 各类指令的平均指令周期和使用频度 指令类别 平均机器周期数/指令 使用频度 访内存 2.5 25% 一般算术逻辑运算 1.25 40% 比较与转移等 1.5 25% 乘除 15 5% 其他 5 5% 若某项事务处理工作所要执行的机器指令数是:控制程序(以访问内存、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,旦指令使用频度基本如表3-1所示,则该计算机系统的事务处理能力约为 (6) 项/秒。若其他条件不变,仅提高主振频率至150MHz,则此时该计算机速度平均约为 (7) 兆条指令/秒,对上述事务的处理能力约为 (8) 项/秒。若主频仍为100MHz,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,此时,计算机的速度平均约为 (9) 兆条指令/秒。
A. 1
B. 5
C. 10
D. 15
E. 20
F. 33.3
G. 50
H. 66.7
I. 100
阅读下面的短文,文中有15处空白,每处空白给出了4个选项,请根据短文的内容从4个选项中选择1个最佳答案。How the Body Keeps the Same Temperature The temperature of your body should be always just the same, no matter whether the weather is trot or cold. That is why the doctor uses his thermometer when you are sick. When you are well,your temperature is ninety-eight and six tenths degrees. If he finds it (51) than that,it is a sure sign that something is wrong. The body keeps the same temperature all the time,because it balances (平衡) the heat it produces and (52) off. It is always burning up food and producing heat. It can produce heat faster when it needs to or give off heat faster when it becomes too warm. Let’s see (53) this happens. The heat of your body is given off chiefly through the skin. When you are (54) ,your skin is tight and shows "goose flesh". When you get chilly (寒冷的),you must dance around to keep warm or (55) you will shiver (颤抖). (56) your muscles begin to work,burn up fuel,and produce more heat. It is not (57) to shiver,so you usually prefer warming up by exercise, or put (58) more clothes to keep heat in. When you are warm,the skin is loose and soft. It is so supplied (59) blood that heat is given off rapidly. If you get too hot,you begin to sweat,and (60) body heat is used in evaporating (蒸发) the moisture (潮湿) from your skin. You wear less clothing, too, in warm (61) or in a warm room,so that warmth can be given off freely. You feel you don’t (62) exercising because your body is warm (63) ,and the extra heat produced by exercise makes you uncomfortable. You can see from this why you (64) differently in different kinds of weather. In summer,when it is warm,you feel tired and lazy. You do not care to work or play,but enjoy lying and doing nothing. When you get out of doors in winter,the cold air makes you feel (65) . You want to run and play.
A. more
B. enough
C. many
D. little