提示：李明打电话给David，邀请他下星期日去博物馆看展览。
(L=Li Ming; D=David)
L: Hello. This is Li Ming speaking. May I speak to David?
D:_____（51）.What'sup, Li Ming?
L: What are you going to do next Sunday?
D: Nothing much. Do you have any ideas?
L:_____（52）? There's a Russian oil painting exhibition there.
D: Good idea! _____（53）?
L: Bus 202 will take you there
D: Good. _____（54）, then?
L: Let's meet just at the gate of the museum.
D:_____（55）
L: Half past nine.
D: All right. See you then.
51._____.
This is David
