用化学方法很难区分丙酮和丁酮，而用₁H¹核磁共振波谱却很容易区分，这是因为______。
   A．它们的核磁共振波谱中的峰数目不相同
   B．它们的氢核受到的外磁场强度不同
   C．它们的氢核的数目不相同
   D．由于核磁共振仪的分辨率高

China's Housing Bubble Trouble Is there a property bubble emerging in China?As ever,getting an answer is like nailingjelly to a wall.Property prices across 70 large and medium-sized cities rose 3.9%on year inOctober.Still,a recent World Bank report suggests that income growth in China is keepingup with price rises.And fundamental demand for improved housing should provide longterm support for Chinese house prices. 点击查看答案

荧光分光光度计的检测器之所以与激发光成直角，是因为______。 A．要防止荧光损失和激发光过强 B．减小激发光的干扰和防止激发余光损伤检测器 C．要提高测定的灵敏度 D．减小仪器的体积

A.要防止荧光损失和激发光过强

B.减小激发光的干扰和防止激发余光损伤检测器

C.要提高测定的灵敏度

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