题目

光合作用产生下列哪一组物质用于卡尔文循环?  (  ) A．ATP和ADP       B．NADH和NADPH  C．ATP和NADPH    D．糖类和氧气 答案：CNo matter how bright a talker you are, there are times when it's better ________ silent. [     ]A. remain  B. be remainingC. having remained  D. to remain