If people keep polluting the rivers, no fish there will survive ______.

A．at all costs

B．once in a while

C．in the long run

D．by no means

Na⁺泵的特点是

A．可造成离子势能的储备

B．腺苷酸环化酶提供能量

C．泵出Na⁺和泵入K⁺交替进行

D．泵出K⁺和泵入N⁺的比例是2:3

E．Na⁺泵是膜上的腺苷酸环化酶