题目

14. It was a _____ evening and I really had a good sleep. A. calm                  B. silent              C. quiet                  D. safe and sound 答案：B一个电路上装有甲、乙两根熔丝，甲熔断的概率为0.85，乙熔断的概率为0.74，甲、乙两根熔丝熔断相互独立，则至少有一根熔断的概率为                                   (　　)A．0.15×0.26＝0.039B．1－0.15×0.26＝0.961C．0.85×0.74＝0.629D．1－0.85×0.74＝0.371