题目

完形填空（共20小题；每小题1.5分，满分30分） 阅读下面短文，从短文后所给题目的四个选项（A、B、C、D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。 It was just getting dark. There was a touch of fog and I was on a lonely stretch of road. __21__, I was going along cheerfully, thinking about the dinner I would eat when I got to Salisbury . I was going along __22__ at about thirty-five miles an hour when suddenly I heard a scream, a   __23__ scream ---“Help!” I looked round, but the only __24__ of life was a la从H、C、O、S、Ca五种元素中选择适当的元素组成符合下列要求的物质，并将化学式填入空格中：（1）可作建筑材料的盐______，（2）可除铁锈的酸______，（3）可作燃料的有机物______，（4）可改良酸性土壤的碱______，（5）金属氧化物______．