1、Lesson 12 Firewalln1.The definition of firewall;n2.The classification of firewall (1)Simple traffic recording system (2)IP packets filter gateway (3)proxy application gatewayn3.Two types of rules used for examining the data traffic (1)default permit (2)default denyNotesn1.When we talk about the Inte
2、rnet, we have to be very careful to identify the fact that the Internet and intranet are actually the same physical network.n 这里的 that the Internet and intranet are actually the same physical network引导的是同位语从句。同位语从句用于对前面出现的名词作进一步说明，一般用连词 that引导。常见的先行名词有 fact, idea, belief, news, hope, conclusion, sug
3、gestion, order, problem, report, decision等。例如：n She finally made the decision that she would join the fashion show.n I had no idea how many books I could borrow at a time.n The news came that their team had won the championship.n 本句译为：当我们讨论互联网时，如果我们细心一点的话可以发现一个事实，就是互联网和内部网实际上是同一个网络。n2.That boundary
4、is nothing but a conceptual entity. The boundary is something weve decided to define as being the point at which we will stop things that are inappropriatethe point at which we can no longer rely upon who is coming in, who is identifying themselves, or how the data may have arrived at our doorstep.n
5、 由于句子过长，采用分译法。n 本句译为：这界限其实是一个概念上的实体，是我们决定用来界定我们需要阻挡的不适当事物的分界点。在这点上，我们将不再依赖信息诸如谁要进来，谁在识别他们自己，或者信息将怎么达到我们的门口。n3.Generally speaking, the latter is better, for it doesnt need to update its checking list often, because it only let the preauthorized users to access in and turn down all the unauthorized ac
6、cessing, no matter what kind of intruders they are, known and unknown.n 这里的 no matter what kind of intruders they are, known and unknown引导的是让步状语从句。引导让步状语从句的连词和词组有 though, although, whether, even though, even if, no matter what(when, how), whatever(whenever, however) 等。例如：n No matter what you may say
7、, I would not change my mind.n 本句译为：总的来说，后者好一点，因为它不需要经常更新它的检查标准，它只让预先授权的用户进入并拒绝所有非授权的进入，无论是已知的或未知的入侵者。小技巧 :Skills of Writing n 提纲式作文（段首句作文）写作技巧n 段首句作文 (Beginning-sentence composition)是一种控制性作文。段首句可以用英文给出的三个段首的第一句或段落的主题句，也可以用中文给出的三个段首的中文提纲。这类作文要求我们按所给每个段落的第一句续写，完成该段落，并尽量表达题目设计者所要表达的思想。同时还要求续写必须与段首句在意义上连成一体，形式上互相统一，语气上一气呵成。否则就会扣题不紧，脱离题目设计者的意图，这是段首句作文的大忌，也是段首句作文成败的关键。为此，我们在写段首句作文时，必须遵循下述步骤：
