肾脏调节血液pH是通过()

A．排泄固定酸保留并维持血中碱储

B．氯离子重吸收

C．钠钾交换

D．碳酸氢根离子的重吸收

E．以上都不是

I regret ________ that you have failed the exam, but what you should do now is not to regret ______ so much time but to seize every moment from now on.

A．to inform; wasting

B．informing; to waste

C．to inform; to waste

D．informing; wasting