We should unite, for no country _____can solve the problem of the pig flu.

 They have earned lots of money, so I______ believe that the business is a success. 

Running a company is not ______ a matter of hiring people---they also need to be trained.

After ten years abroad, he still recognized his old colleagues ________ he set foot in China．

Fortunately somebody who happened to be passing by called the emergency aid        the traffic accident occurred.