题目

阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。Onething that sets cycling apart from most other sports at the Olympics istechnology. With the exception of a few other sports, such as sailing androwing, most events that take place at the Summer Games usually just come downto the performances of the athletes. They try to swim and run faster, jump andclimb higher, lift and hit with more strength.Incycling, the competition is so close-often a hundredth of a second separatesriders-that the difference in winning and losing can be found in the chain, thewheels下列有关元素的性质及其递变规律正确的是（ ）A．ⅠA族与ⅦA族元素间可形成共价化合物或离子化合物B．第二周期元素从左到右，最高正价从+1递增到+7C．同主族元素的简单阴离子还原性越强，水解程度越大D．同周期金属元素的化合价越高，其原子失电子能力越强