下列各项中，属于民事法律行为的有()。A.甲商场与某电视生产企业签订购买一批彩电的合

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．

（74）处填（）。

A．power

B．rights

C．authorized

D．common

下列那些是人乳与牛乳相比的优点（）

A.蛋白质含量比牛乳多

B.乳白蛋白含量多

C.蛋白质遇酸后凝块小

D.乳铁蛋白对免疫有帮助

E.酪蛋白含量少

在优化企业模型的工作中，成功与否的关键是

A．企业业务部门和信息部门的通力合作

B．系统分析人员和程序编制人员的认真沟通

C．企业领导和各级管理人员的全力支持

D．企业业务部门和上级管理部门的紧密协调

“突然青天里一个霹雳/爆一声/咱们的中国”与“等到青天里一个霹雳/爆一声/咱们的中国”用了什么修辞手法及其作用？