经研究证明，各种能形成异形胞的蓝细菌都具有固氮能力。
参考答案：对
— There is still a copy of this book in the library. Will you go and borrow _____?
— No, I will buy _____ in the bookstore. [ ]
A. one; it
B. one; one
C. it ; one
D. it; it
