改复数 单数形式复数：This is a good doctor I'm an English teacherIt is

复数
This is a good doctor
【These are good doctors.】
I'm an English teacher
【We're English teachers.】
It is a Knife
【 They are knives.】
He has a new watch
【They have new watches.】
What's this?It's an orange
【What are these?They're oranges.】
This is my dress
【These are my dresses.】
单数：
Those are green jeeps
【That is a green jeep.】
They are old cars
【It is an old car.】
What are those?They are erasers
【What is that?It is an eraser.】
Are they American Girls?
【Is she an American girl?】