Cathie didn't know(where could we buy the tickets/what was he waiting for)因该选哪个

Cathie didn't know(where could we buy the tickets/what was he waiting for)因该选哪个
Cathie didn't know(where could we buy the tickets/what was he waiting for)因该选哪个

Cathie didn't know(where could we buy the tickets/what was he waiting for)因该选哪个
后面的 因为宾语从句要用陈述句语态哦!