Jack and Susan _______ each other since they were children, so nobody was surprised to hear that they were married.

A. knew          B. had known        C. have known    D. were known

 Jack and Susan ________ each other since they were children, so nobody was surprised to hear that they were married.

A. knew         B. have known    C. had known     D. were known

用括号内所给动词的适当形式填空，并将答案写在答题卡标有题号的横线上。
【小题1】Many great changes ____________ (take) place in China during the past 10 years.
【小题2】We should think about all we can do ____________ (prevent) animals and plants from becoming endangered.
【小题3】Today, to hold the Olympic Games ______________ (consider) as a rich prize for a country.
【小题4】The engineers ____________ (search) for some information on the Internet in the laboratory when Mr. White arrived.
【小题5】Jack and Susan ____________ (know) each other since they were children, so nobody was surprised to hear that they got married.
【小题6】He promised that he ___________ (not forget) to hand in his report before weekend.
【小题7】The patient jumped excitedly when he heard his illness could ______________ (cure).
【小题8】We should try out best to stop those factories ____________ (pollute) the rivers again.