that is a pen /that is the pen有什么区别?

that is a pen /that is the pen有什么区别? that is a pen This a pen.that is a pen,什么 That is green pen That is your pen that is your pen. That is _____.It is very nice.A.pen B.my pen C.the pen D.the you should draw with pen,that is,in a pen Is that your pen on the desk? That is a pen.(变为复数) that is a pen (变为复数） Is that a pen?的同意句