問題詳情

14. To be useful to plants soil nitrogen must usually occur as:
(A) N2 and NH3
(B) NH3 and NO3-
(C) NO3-and N2
(D) N2 and NO2
(E) NO2 and NO3-

參考答案

答案:B
難度:簡單0.761905
統計:A(1),B(16),C(1),D(0),E(2)