Private companies have little interest in producing flu vaccines because of______.
A. complicated process, high cost, low profit and high risk
B. shortages of fertilized chicken eggs
C. difficulty in growing live virus
D. fast changing of flu virus
Dr. Wilson suggests that Wang should extend his stay at the university.
A. True
B. Fasle
听力原文：What color is it？
(8)
A. It's an apple.
B. It's red.
C. It's very kind of you to say so.
St. Duke's School is big and nice.
A. True
B. False
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