Giải thích vì sao lại viết như thế

Giải thích vì sao lại viết như thế
GRAMMAR MULTIPLE CHOICE:
1. As soon as Martina saw the fire, she ______ the fire department.
A. was telephoning        B. telephoned       C. had telephoned       D. has telephoned
2. Jane’s eyes burned and her shoulder ached. She ______ at the computer for five straight   hours.
A. is sitting       B. has been sitting        C. was sitting       D. had been  sitting
3. The man who sat beside me on the plane _____ nervous. He _____ by air before.
A. looked/ has never traveled       B. looked/ had never traveled    C. was looking/ never traveled       D. looked / was never traveling
4. The Second World War _______ in 1939 and _______ in 1945.
A. begins/ ends      B. had begun / ended       C. began/ had ended       D. began /ended
5. It seems that whenever I travel abroad, I _______ to take something I need.
A. forgot      B. am forgetting      C. forget      D. had forgotten
6. I _______ Casablanca for the first-time last night. I _______ it before.
A. saw /had never seen      B. see /have never seen    C. have seen /never saw       D. was seeing /had never seen
7. Yesterday Ann introduced me to her husband. As I saw him, I ______ that I ______ him   before. We went to primary school together.
A. knew / met      B. had known / had met        C. knew /had met       D. had known / met
8. I _______ you sooner if someone _______ me you were in the hospital.
A. would visit / told       B. will visit /tells      C. had visited / would have told      D. would have visited / had told