题型:选择题 下列说法中正确的是( )A.硫在空气中点燃,发出明亮的蓝紫色火焰B.铁在空气中剧烈燃烧,火星四射,生成黑色固体C.红磷点燃后伸入氧气集气瓶中,产生大量白色烟雾D.石蜡在氧气中点燃后产生无色气体并发出白光 查看答案
题型:选择题 ---What did you say to Julia? I saw her crying in the dormitory alone. --- It ______ my fault. We talked happily when I was with her in the classroom.A.mustn’t have beenB.should have been C.shouldn’t have been D.couldn’t have been 查看答案
题型:单项选择题 预应力筋的张拉程序,主要根据构件类型、张锚体系、松弛损失取值等因素确定。用超张拉方法的作用是()A.增加预应力筋的松弛损失B.对钢筋实施冷拉C.减少预应力筋的松弛损失D.对钢筋实施冷拔 查看答案