________ advertisements are of great help, I don’t think we should entirely rely on them.
| A．Because | B．Since | C．Once | D．While |
Wherever I ____these days. I always carry my umbrella.
| A．am going | B．shall go | C．go | D．should go |
It is five years since my dear aunt _______ here.
| A．left | B．has left | C．is left | D．had left |
It ________ nearly two weeks ______ I had received his letter.
| A．is, that | B．was, that | C．is since | D．was, since |
----This returned Chinese scholar has become one of the top experts in this field.
----Yes,I know him very well.He____in Africa with animals for eight years.
| A．has worke | B．had worked | C．worked | D．has been working |
----Does Liu Hua serve in the army?
----No,but he ___in the army for three years.
| A．served | B．has served | C．is serving | D．would serve |