定点8位字长的字，采用补码形式表示时，一个字所能表示的整数范围是______。

(81)

(80)

(79)

(78)

Most computer systems are (71) to two different groups of attacks：insider attacks and outsider attacks．A system that is known to be (72) to an outsider attack by preventing(73) from outside can still be vulnerable to the insider attacks accomplished by abusive usage of (74) users．Detecting such abusive usage as well as attacks by outsides not only provides information on damage assessment,but also helps to prevent future attacks．These attacks are usually (75) by tools referred to as Intrusion Detection Systems．

(77)

(76)

(73)

(75)

对象是面向对象开发模式的(47)。每个对象可用它自己的一组(48)和它可执行的一组(49)来表征。应用执行对象的(49)可以改变该对象的(48)。

(74)

(72)