Period Four　Grammar-The use of "it"(2)

感知以下课文原句，补全方框下的小题

1．There is no doubt that the earth is becoming warmer(see Graph 1) and that it is human activity that has caused this global warming rather than a random but natural phenomenon.

2．It was a scientist called Charles Keeling who made accurate measurements of the amount of carbon dioxide in the atmosphere from 1957 to 1997.

3．They also agree that it is the burning of more and more fossil fuels that has resulted in this increase in carbon dioxide.

这些句子都是强调句型，句中的划线部分标出了句中的强调结构，即：it is/was＋被强调部分＋that/who＋其他。句首用it，be动词总是用单数形式，即is或was，连接词一般用that，当被强调部分是"人"时，连接词也可用who。

强调句型中的it：

1．肯定句

It is (was)＋被强调部分＋that (who)＋其他部分：

It was in Beijing that I saw the film Wolf Warriors Ⅱ.

我是在北京看了电影《战狼Ⅱ》。

2．否定句

It is (was) not＋被强调部分＋that (who)＋其他部分

It is (was) not until...＋that＋其他部分：

It was not for several years that I had an opportunity of seeing him again.

＝I did not have an opportunity of seeing him again for several years.

我有好几年没有机会再见到他了。

It was not until twelve o'clock last night that he went to bed.

＝He didn't go to bed until twelve o'clock last night.

昨晚他12点才去睡觉。