问题 单项选择题

系统抖动是指______。

A.使用机器时,屏幕闪烁的现象

B.系统盘有问题,致使系统不稳定的现象

C.被调出的页面又立刻调入所形成的频繁调入调出的现象

D.由于内存分配不当,偶然造成内存不够的现象

答案

参考答案:C

解析: 本题考查点是系统抖动。虚拟存储管理中可能出现系统抖动的现象,即刚被淘汰(从内存调到外存)出去的一页,时隔不久又要访问它,因而又要把它调入,调入不久又再次被淘汰,再访问,再调人,如此反复,使得整个系统的页面调入调出工作非常频繁,以致大部分CPU时间都用在来回进行页面调度上,只有很少一部分时间用于作业的实际计算,这种现象称为系统抖动,也称为颠簸。系统抖动使得整个系统的效率大大下降,甚至趋于崩溃,系统应立即采取措施加以排除。

阅读理解与欣赏
单项选择题

College sports in the United States are a huge deal. Almost all major American universities have football, baseball, basketball and hockey programs, and (1) millions of dollars each year to sports. Most of them earn millions (2) as well, in television revenues, sponsorships. They also benefit (3) from the added publicity they get via their teams. Big-name universities (4) each other in the most popular sports. Football games at Michigan regularly (5) crowds of over 90, 000. Basketball’s national collegiate championship game is a TV (6) on a par with any other sporting event in the United States, (7) perhaps the Super Bowl itself. At any given time during fall or winter one can (8) one’s TV set and see the top athletic programs--from schools like Michigan, UCLA, Duke and Stanford-- (9) in front of packed houses and national TV audiences.

The athletes themselves are (10) and provided with sch61arships. College coaches identify (11) teenagers and then go into high schools to (12) the country’s best players to attend their universities. There are strict rules about (13) coaches can recruit--no recruiting calls after 9 p. m. , only one official visit to a campus--but they are often bent and sometimes (14) . Top college football programs (15) scholarships to 20 or 30 players each year, and those student-athletes, when they arrive (16) campus, receive free housing, tuition, meals, books, etc.

In return, the players (17) the program in their sport. Football players at top colleges (18) two hours a day, four days a week from January to April. In summer, it’s back to strength and agility training four days a week until mid-August, when camp (19) and preparation for the opening of the September-to-December season begins (20) During the season, practices last two or three hours a day from Tuesday to Friday. Saturday is game day. Mondays are an officially mandated day of rest.

20()

A. in principle

B. in confidence

C. in name

D. in earnest