Unit 4 Global warming Grammar

it的用法（2）学案

　　语法图解

　　探究发现

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

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

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

　　④It was during the 20th century that the temperature of the earth went up about one degree Fahrenheit.

　　[我的发现]

　　这些句子都是强调句，句中的黑体词部分标出了句中的强调句结构，即：it_is/was＋被强调部分＋that/who ...句首词用"it"；be动词总是用单数形式，即is或was。连接词一般用that，当强调部分是人时，强调连接词也可用who。

　　一、强调句的基本用法

　　强调句就是把句中要强调的部分(通常是主语、宾语、状语或状语从句)放在It is/was和that/who之间，原句中剩余部分放在that/who之后。

　　1．强调句的陈述句式

　　"It is/was＋被强调部分＋that/who＋其他剩余部分．"

　　The 2022 Winter Olympic Games will take place in Beijing and Zhangjiakou.

→It is in Beijing and Zhangjiakou that the 2022 Winter Olympic Games will take place.