that(复数) this(复数) brother(对应词) is(复数) boy(复数) I(形

that(复数) this(复数) brother(对应词) is(复数) boy(复数) I(形 Is that boy your brother 改复数形势 This is my brother.(改为复数） This is my brother.改为复数形式 Is this yuor brother改成复数形式 That is his brother的复数形式 That is her brother.(改为复数句) that is his brother 改为复数句 is that your brother 改为复数 This boy is pupil（变复数) that boy is good.改复数 this that的复数