A:Hi, Ms. Miller. .
B:Good morning, Jim. Jack found a set of keys. ?
A:Yes, they are. Thanks. Did you find a schoolbag?
B:Oh, some schoolbags are here. Which one(哪个) is yours? ?
A:It's white.
B:Is this your schoolbag?
A:. It's white, but it's not mine.
B:And is this your schoolbag?
A:Yes, it is. Thank you, Ms. Miller.
B:.