---How long does it take us to go to Mount Qingcheng?
---It takes us hour or more to go to Mount Qingcheng by subway
A.an;a B.a;an C.an;/
---How long does it take us to go to Mount Qingcheng?
---It takes us hour or more to go to Mount Qingcheng by subway
A.an;a B.a;an C.an;/