计算机英语章节知识点unit13

Unit Thirteen
1 When a separate server is used as a gateway，
as : 用as 还是用like
（1）在跟动词的名词以前用like ，不用as
she sings like a bird does .
(2) 在副词前面用as 不用like :
we have to be realistic on occasions when ,as now ,we have no option.在目前，我们没有其他的选择，我们必须是现实主义的。

(3)在介词或在应该有介词的地方以前要用as 不用like .
He is now busy writing a book in which ,as in his last, he discusses the implications of modern genetics.
（4）在相同结构的两句中，用as 的和用like 的意义不同：
let me speak to you like a father .(让我像是你自己父亲一样对你讲话)（实际上我虽然并不是你的父亲）
Let me speak to you as a father 。

（让我以我是你父亲的身份对你进话）。

（实际上我是你的父亲）
注意：as 侧重同一性，意味着属于同一类，或完全相似。

Like 侧重于比较，不意味着属于同一类或完全相似。

同时，as 即可作前置词（通常指用来引出同位语，表语，补语），又可作连接词（引导从句）。

Like 通常只用作前置词。

2 bridge simply looks at the packet address to see where it is going----
look at：作看，瞧。

Look 经常与at 连用，有时也单独使用。

look before you leap.
She looked at the people around her .
注意：look see 和watch 的区别，look at 主要指“看着” see 主要指“看见”watch 主要指“注视”
3 ---it is bound for another network，---
be bound for ：表示准备前往；在前往---的途中。

（be ready to start for , be on the way to）where are you bound for ?( where are you going ?)
4 -----between the various protocol layers.
Various ：各种各样的。

这次不能用作代词。

不能说：I asked various of the children 应说：I asked some/several of the children 或I asked various children.
5 leased line : 租用线路。

6Bridges are ideally suited to interconnecting similar networks in which---
Be suited to : appropriate ;适合。

a person who is well suited to the job .
7buildings and keeps it off the superhighway.
keeps off：远离。

制止，抑制。

Please keep off that subject ,say nothing about .
8types of network resources.
Type（types ）of : 可跟单数或复数名词，不论名词的单数和复数一般都不用冠词。

9 A router is similar to a bridge—
is similar to: similar 指事物之间的“相像的”“类似的”与same 不同的是，他不含又同一的意义。

在句中作定语和表语。

作表语时，不与冠词连用，其后可接介词to 和in 引导
his house is very similar to mine in appearance .
Girls wear fashionable clothes to attract boys .In a similar way ,some birds have bright feathers . 女孩们穿上时装来招引男孩们。

以类似的方法，有些鸟类拥有鲜艳的羽毛。