QQ,________you can chat with your friends, makes communication easy.
| A．why | B．which | C．that | D．where |
The trouble is _____ we are short of hands.
| A．what | B．that | C．how | D．why |
. The guide showed the travelers _____ of the factory.
| A．in | B．out | C．off | D．around |
We should mind our behaviour ______ public.
| A．at | B．in | C．on | D．out |
They made a bet _____the white horse.
| A．for | B．with | C．on | D．in |
. He _____ himself in Shanghai.
| A．lost | B．missed | C．losing | D．missing |