成人主要血红蛋白(HbA)由哪几条肽链组成()
A.两条α和两条β肽链
B.两条α和两条δ肽链
C.两条α和两条γ肽链
D.两条β和两条γ肽链
E.两条β和两条δ肽链
参考答案:A
English __________ in our school for almost 60 years.
A.has taught
B.was taught
C.had been taught
D.has been taught
A.沿ON前后转动板E
B.沿ON前后转动板F
C.改变光线OB与ON的夹角
D.改变光线AO与ON的夹角