铀裂变的产物之一氪是不稳定的,它经过一系列衰变最终成为稳定的锆,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
答案:B
小题1:It didn’t occur on me that you would be against it. ____________________________
小题2:We could hardly believe the high price marking on the goods
小题3:The fact which he had not said anything surprised everybody. ______________________
小题4:We are discussing whether we should team up other students to hire a car.
小题5:Cotton take in water.
患者女性,62岁,因脑血管病变后遗留麻痹,存在吞咽困难一年,对其进行营养支持最宜采用的是()
A.留置鼻胃管鼻饲
B.留置鼻空肠管鼻饲
C.完全胃肠外营养支持
D.经皮内镜下胃造口术(PEG)
E.手术胃造口术