引导名词性从句的连接词用于现在完成时的句型
引导名词性从句的连接词
比较：whether与if 均为"是否引导名词性从句的连接词可分为三类：
连接词：that,whether,if 不 充当从句的任何 成分）
连接代词：what, whatever, who, whoever, whom,
whose, which.
连接副词：when, where, how, why 不可省略的连词：
1. 介词后的连词
2. 引导主语从句和同位语从句的连词不可省略。
That she was chosen made us ve ry happy.
We heard the news tha t our team had won.
"的意思。但在 下列情况下， whether 不能被if 取代：
初二下册英语电子课本
速记英语单词的方法
高中英语课本人教版
2. 引导表语从句
3. wh ether从 句作介词宾语
4. 从句后有"or not"
Whether he will come is not clear.
大部分 连接词引导的主语从句都可以置于句末，用 it充当形式主语。
It is not important who wil l go.
It is still unknown which team will win the match.
用于现在完成时的句型
1）It is the first / second time…. that…结构中的从句部分，用现在完 成时。
It is the first time that I have visited the city.
It was the third ti me that the boy had been late.
2）This is t he… that…结构，that 从句要用现在完成时.
This is the bes t film that I've (ever) seen.
这是我看过的最好的电影。
This is the firs t time (that) I've heard him sing. 这是我第一次听他唱歌。
典型例题
(1) ---Do you know our town at all?
---No, this is the first time I ___ here.
A. was B. have been C. came D. am coming
答案B. This is the first time 后面所加从句应为现在完成时，故选B。
(2) ---Have you ____ bee n to our town before?
---No, it's the f irst time I ___ here.
A. even, come B. even, h ave come C. ever, come D. ever, have come
答案D. ever意为曾经或无论何时，反意词为never，此两词常用于完成时。 This is the largest fish I have ever se en. It is / was the first time +that-clause 的句型中，从句要用完成时。
注意：非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是可以持续的。
（错）I have rece ived his letter for a month.（对）I haven't received his letter for almost a month.
