we found it necessary to protect the earth 为什么用it 而不是it is

来源：学生作业帮编辑：作业帮分类：英语作业时间：2024/05/22 01:12:40

从语法上讲,用 it和it is 都是可以的.区别在于,
We found it necessary to protect the earth（我们觉得保护地球十分必要）是一个简单句,其结构是主+谓+it（形式宾语）+宾语补足语+宾语,we做主语,found做谓语动词,后面的to protect the earth是真正的宾语,necessary显然就是宾语补足语了,it在这里是形式宾语,用它是因为宾语偏长,避免头重脚轻；
We found it is necessary to protect the earth
（我们觉得保护地球是十分必要的）是一个复合句,其结构是主+谓+it（从句的形式主语）+连系动词（is）+从句的表语+从句真正的主语（不定式）found后面的整个句子做它的宾语,因为it is necessary to protect the earth是一个完整的主主系表结构,在这个从句里,it做从句的形式主语,同样也是为了避免头重脚轻,后面的不定式to protect the earth做真正的主语,necessary是表语.
很明显,二者的区别在于第二句是一个主从复合句,而前者是一个简单句,出于尽量用简单的成分表达同样的意思的目的,用it更好.希望可以对你有所帮助.

we found it necessary to protect the earth 为什么用it 而不是it is We find ______ necessary to protect the earth.A.it B.this C. It is necessary to protect trees from the frost. The p__ Earth is our home.We should protect it. it is necessary to protect our traditional culture 英语作文it's important to protect the earth We find ___ necessary to protect the earth. I think that it is necessary in protect the environment.用英语怎 it is important for us to protect the earth.改为同义句 We found it was necessary to write down her addresss.请用：find We have only one earth and we should 什么 to protect it 英语语法She learned it necessary to protect the wild animals.nec