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【多选题】
关于维生素D,下列说法正确的是A.
对于大多数畜禽来说维生素D3的效价高于维生素D2
B.
VD生物活性最强的形式为1,25-二羟胆钙化醇
C.
主要生理功能是增强肠道钙、磷的吸收,以及肾脏和骨骼中钙和磷的重吸收
D.
畜禽VD的主要缺乏症是肌肉营养不良
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【单选题】What does the man mean when he says this:
A.
He wants to change the topic of the talk.
B.
He wants the professor to elaborate on a point in the lecture.
C.
He is trying to remember something the professor already said.
D.
He wants to correct some mistakes that the professor made.
【单选题】听力原文：W: There is a man in the reception area. He says he has an interview with Louis at 11:30. M: Oh, Louis must have forgotten about that. His parents came to visit him from Boston and he's probably ...
A.
In a meeting room
B.
At the office
C.
In Boston
D.
In New York
【单选题】听力原文： US President George W. Bush says he recognizes human beings contribute to global climate change but he remains unyielding in his opposition to the Kyoto Accord on the issue. Bush made the remark...
A.
To call on more effort to reduce human beings' contribution to global climate change.
B.
To include more developing countries into the Accord.
C.
To continue to oppose to the Accord.
D.
To sign the treaty to cut emissions of carbon dioxide.
【简答题】当外界存在一个很强的干扰信号,由于收信机的非线性仍能造成对有用信号增益的降低(受到抑制)或噪声提高,使接收机灵敏度下降,这种干扰称为( )干扰. A. 同频道 B. 邻道 C. 杂散辐射 D. 阻塞
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