Who's this?A This is … B It's … C He's …应选哪一个好,为什么?人教新目标七上的答案为B，为什么呢，望各位尽量给出为什么？

-()?-This is Chen Jie spaking.A Who are youB Who's this C Who's that ______book is this?It s mine.A who B who's C whose D whose's 改错Who's book is this?（） 改错 Who's book is this? This is Ben( ).Who's that,please ________ bike is this?B:It’s mine.A.whose B.who C.who’s who is that?A.That's a student B.It's Bob C .This is Bob A:______pen is this?B:It's Wang fang's.A.Who's B.Whose .___notebook is this?A.who B.who's C.what D.whose B:Hello,this is Bill s( ).Who is that?A:It's Ann h(). Who is that?Oh,--------- Michael.A.this is B.it's C.his D.that's _______ this?A Whose is bag B Whose bag is C Who's bag D Who's is bag Who's this? who's this boy? Who's this?... Idon't know ___book this is.A.who B.whomIdon't know ___book this is.A.who B.whom C.whose D.who's This is a man who i said Who is this man?