要保证文化创新沿着正确的方向、采用正确的方法进行，必须克服“守旧主义”和“封闭主义”以及“民族虚无主义”和“历史虚无主义”的错误倾向
Animals do many different, amazing things to get through the winter. Some of them “migrate.” This means that they travel to other places where the weather is warmer or where they can find food.Man
（12分）现有部分短周期元素的性质或原子结构如下表：元素编号元素性质或原子结构TM层上的电子数是原子核外电子层数的2倍X最外层电子数是次外层
—Do you have any idea what Paul does all day? —As I know，he spends at least as much time playing as he ________. A. writes B. does writing C. is writing
既可以用来鉴别乙烷和乙烯，又可以用来除去乙烷中混有的乙烯的方法是：A．在空气中燃烧 B．通入足量溴水中C．通入酸性高
物质在水中可能存在电离平衡、盐的水解平衡和沉淀的溶解平衡，它们都可看作化学平衡．请根据所学知识的回答： （1）A为0.1mol/L的（NH4）2SO4溶液，
(18分)质量为m，长为L的矩形绝缘板放在光滑水平面上，另有一质量为m，带电量为q的小物块沿板的上表面以某一初速度从左端A水平向右滑上该板，整个
