题目

阅读理解Today, an increasing number of people are always looking attheir mobile phones with their heads down. These people are called the Heads-downTribe(低头族). Are you a heads-down tribe member? Heads-down tribe membersnow can be seen everywhere.More and more traffic accident are happening because driversuse mobile phones when they are driving. In order to make drivers pay more attentionto driving, some new traffic rules have been made. For example, heads-down tribemembers who use mobile phones while driving will be fined（处罚））¥200.As we can see above, using mobile phones m已知X、Y元素同周期，且电负性X＞Y，下列说法错误的是            （       ） A．X与Y形成化合物时，X显负价，Y显正价 B．第一电离能Y一定小于X C．最高价含氧酸的酸性：X对应的酸性弱于Y对应的酸性 D．气态氢化物的稳定性：HmY小于HmX