题目

Much to our disappointment, this clothing factory was horribly managed and ______. A . out of reach B . out of shape C . out of order D . out of practice 答案：C铀裂变的产物之一氪90（）是不稳定的，它经过一系列衰变最终成为稳定的锆90（），这些衰变是 [     ]A.1次α衰变，6次β衰变B.4次β衰变 C.2次α衰变 D.2次α衰变，2次β衰变