题目

短周期的三种元素X、Y、Z，原子序数依次减小，原子核外电子层数之和是5。X元素原子最外电子层上的电子数是Y和Z两元素原子最外电子层上的电子数的总和；Y元素原子的最外电子层上的电子数是它的电子层数的2倍，X和Z可以形成XZ3的化合物。请回答    （1）X、Y、Z元素的名称分别是X       Y       Z       。    （2）XZ3化合物的化学式是               ，电子式是                  。    （3）分别写出X、Y的最高价含氧酸的化2、I suddenly heard an elephant crying as though frightened. Looking down I immediately recognized that something was wrong and ran down to the edge of the near bank. There I saw Ma Shwe with her three-month-old calf struggling in the fast-rising water and it was a life-and-death struggle. Her calf was floating and screaming with fear. Ma Shwe was as near to the far bank as she could get, holding her whole body against the rushing water and keeping the calf pressed against her huge body. Every now and then the rushing water would sweep the calf away. There was a sudden rise in the water and the calf was washed clean over the mother’s body and was gone. Ma Shwe turned quickly to reach it and pressed the calf with her head and trunk（象鼻）against the rocky bank .Then with a huge effort she picked it up in her trunk and tried until she was able to place it on a narrow shelf of rock. Just at this moment she fell back into the river .If she were carried down ,it would be certain death. I knew as well as she did ,that there was one spot（地点）where she could get up the bank  but it was on the other side from where she had put her calf While I was wondering what I could do next, I heard the sound of a mother’s love. Ma Shwe had crossed the river and got up the bank and was making her way back as fast as she could roaring（吼叫）all the time but to her calf it was music. 56．The moment the author got down to the river bank he saw______. A．the calf was about to fall into the river B．Ma Shwe was placing the calf on the rock C．the calf was washed away by the rising water D．Ma Shwe was holding the calf against the rushing water 57．How did Ma Shwe manage to save her calf from the fast-flowing water? A．By putting it on a safe spot B．By pressing it against her body C．By taking it away with her D．By carrying it on her back 58．How did the calf feel about the mother elephant’s roaring? A．It was a great comfort      B．It was a sign of danger C．It was a call for help       D．It was a musical note 59．What can be the best title for the text? A．A Mother’s Love           B．A Brave Act C．A Deadly River            D．A Matter of Life and Death