乳酸循环所需的NADH主要来自（）. A.三羧酸循环过程中产生的NAD_爱下问搜题

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问题单项选择题

乳酸循环所需的NADH主要来自（）.

A.三羧酸循环过程中产生的NADH

B.脂酸β-氧化过程中产生的NADH

C.糖酵解过程中3-磷酸甘油醛脱氢产生的NADH

D.磷酸戊糖途径产生的NADPH经转氢生成的NADH

E.谷氨酸脱氢产生的NADH

答案

参考答案：C

解析：3-磷酸甘油醛脱氢产生的NADH在无氧下传递给丙酮酸以生成乳酸，再生成NAD⁺以继续进行脱氢反应。

选择题

以下四图中昼夜温差最大的是

A、A

B、B

C、C

D、D

完形填空

Until 1954 it was thought that no man could run one mile in less than four minutes.As years went by, the record came closer and closer to four minutes and Roger Bannister，a young English athlete, began to believe he might __11__ this almost magic barrier.
It was a cold afternoon on May 6th, 1954, when Bannister knew he had a __12__ chance.Bannister had been __13__ hard and was very fit, but the weather conditions were a real __14__ to him.Describing the __15__ later, Bannister said, “On the way to the track the wind blew strongly.As I __16__ up for the start I glanced at the flag.It moved __17__ now.This was the moment when I made my decision.”
“The gun fired.My legs seemed to meet no resistance，as if I was __18__ forward by some unknown force.The noise from the faithful __19__ gave me greater strength.I felt the __20__ of a lifetime had come.”
“I was driven on by a __21__ of fear and pride.My body had long since used up all its energy but it went on running just the same.This was the critical moment when my legs were strong enough to carry me over the last few yards as they never could have done in previous years.When I leapt at (冲向) the __22__ tape, I fell, almost __23__.”
“I knew I had done it, even before I __24__ the time.The announcement came, ‘Result of the one mile...Time，three minutes...’ the rest was __25__ in the noise of excitement.”

A．concentration

C．combination

D．satisfaction

A．unconcerned

B．unconscious