I ________in this school for ten years.
A. has worked
B. am working
C. have worked
D. was working
. Tom flew to London by ______.
A. he
B. himself
C. herself
D. themselves
Doctor Wilson _______ a pain in his back since last Sunday.
A. have had
B. had have
C. has had
D. has have
I _______English for ten years before I ______ to teach you in 1997.
A. had studied, came
B. have studied, come
C. studied, came
D. have studied, have come
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