标记蛋白质核酸的活化生物素()
A.N-羟基丁二酰亚胺酯
B.生物素酰肼
C.3-(N-马来酰亚胺-丙酰)-生物胞素
D.光生物素
E.荧光素
参考答案:D
How can you possibly miss the news? It ________ on TV all day long.
A.has been
B.had been
C.was
D.will be
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