下列哪项不是MHC基因编码的产物()
A.MHCⅠ类分子α链
B.MHCⅡ类分子α链
C.MHCⅠ类分子β链
D.MHCⅡ类分子β链
E.C2、C4分子
参考答案:C
—How do you improve your listening skill, Mary?
—I often do it _____ tapes and English radios. [ ]
A. by hearing
B. in listening to
C. by listening to
D. for listening
伤寒宜选
A.四环素
B.多西环素
C.氯霉素
D.氨苄西林
E.白霉素