补全对话.a：excuse me,wangshan,—— b：sorry,i don\t know.——please go and ask ted.
a：excuse me.what time is it,please?
c：it、s about 3:30p.m.
a：thank you,ted.
c：——look,under the desk.
b：is it black?
c：——
b：let me have a look.oh,it、s mine.
c：——
b；thanks very much.