句型转换。  

1.Over three-fourths of the gas is nitrogen.（改为同义句）

                        three-fourths of the gas is nitrogen.  

2. Everything will die on the earth without the atmosphere to protect us.（改为同义句）

    Nothing could ________on the earth without the atmosphere to protect us.

3. The chorus（合唱队）of our school consisted of some students and teachers.（改为同义句）

    The chorus of our school_______       some students and teachers.

4. The river is filling with heavily rain.（改为同义句）  

    The river ________of heavily rain.

5. I found that studying English well is more difficult.（改为同义句）  

    I found        ____more difficult____       English well.