英语周报八年级外研2021-202227期答案

4.D【解析】碳原子有2个电子层,6个电子,核外电子数是电子层数的3倍,W为碳元素;钠的焰色反应呈黄色,X为钠元素,钠离子和氟离子的电子层结构相同,Y为氟元素,氟和氯位于同一主族,Z为氯元素。同周期元素,从左至右原子半径逐渐减小,碳的原子半径大于氟的,A项错误。含Cl元素的酸不一定是强酸,如次氯酸,B项错误。氟化钠是强碱弱酸盐,F水解能促进水的电离,C项错误。非金属性F>Cl,故简单氢化物的稳定性HF>HCl,D项正确。

One possible versionSeveral minutes later, the ice broke suddenly and Harry's feet sank into the water. It was noep, but his legs got wet to the knees. Harry was so upset that the accident would delay hisschedule. He had to find some firewood to build a fire to dry his clothes. He pulled off his glovestook out his matches, and lighted the fire. Seeing the burning fire, he had thought he was safe. Butsuddenly, without warming, a heavy mass of snow dropped down. The flame of hope was put outUnluckily, his dog ran away and the fear of death came over Harry. He had no choice but torun to save himself. However, he did not feel his feet when they hit the ground. Having falleneveral times, he decided to rest a while. As he lay in the snow, he noticed he was not shaking. Hecould not feel his nose or fingers or feet. A feeling of horror came into his mind. It was when herealized he was going to die that he heard a bark and the noise his friends made

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