Is that your grandfather?No, it/he isn't.上面的错了，主语是that，在教科书上一般用it指代，但是用he也行。祝你学习进步，更上一层楼！(*^__^*) 有不会的可以再问我:）
Is that your grandfather?No，he isn't指人确定性别一般不用it有不会的可以再问我
Is this your grandfather? No, this isn't.
