Which of the following is definitely true, according to the passage（）
A. The young people are studying too hard
B. The courses in the youth center are too difficult
C. The government financed the establishment of job-oriented school
D. The tests given to the youngsters are too difficult
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Of the following four immunization routes, which one is the best route for protein antigens（）
A. oral administration
B. intramuscular injection
C. intravenous injection
D. intradermal injection
The substance that can activate a large number of T cells to produce immune responses at very low concentrations is called（）
A. autoantigen
B. allergen
C. common antigen
D. superantigen
Bound morphemes include____（）
A. bound roots
B. inflectional morphemes
C. affixes
D. free morphemes
In which period did Geoffrey Chaucer live（）
A. Old English
B. Middle English
C. Early Modern English
D. Late Modern English
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