【非選題】 13. In many groups of organisms, such as birds and trees, there exists a latitudinal diversity gradient, in which
species richness is highest in low latitudes, and gradually decreases with increasing latitudes. Many hypotheses
have been proposed to explain this pattern. List three hypotheses and provide the rationales. (9 points)
12.About the van der Waals equation, which statement is incorrect?
(A) is the approximate equation of state for real gas
(B) van der Waals coefficients are characteristic of each gas
(C) van der Waals coefficients are independent of the temperature
(D) combine effect of repulsion and attraction
(E) none of the above answer is incorrect