已知为正偶数，且的展开式中第项的二项式系数最大，则第项的系数是 ．（用数字作答）
从生态系统的组成成分看，硝化细菌和蚯蚓分别属于 （ ） A．生产者、消费者 B．生产者、分解者 C．分解者、消费者 D．消费者、分解者
Elizabeth lived with her six children in a small house. One winter, there was a big flood(洪水) ,and quite a few houses were washed away, but Elizabeth's house was high enough to escape it.Elizabeth
建国60年多来，我国逐步完善社会主义政治制度，保障人民当家作主。这些政治制度有（ ） ①中国共产党领导的多党合作和政治协商制度
下列选用的相关仪器符合实验要求的是 （ ） A．分离Fe(OH)3胶体和蔗糖溶液 B．量
（2008年唐山测试）将一株植物培养在H218O中并进行光照，过一段时间后18O存在于 （ ） A.光合作用生成的水中 B.仅在周围的水蒸气中 C.
---- Can you _____ all the money that I should pay now? -----Very sorry, madam. Wait a minute, please. A. add up B. add to C add up to D add
Tom likes swimming，but he doesn't like skating；________. A．neither does his brother B．so his brother does C．nor did his brother D．so it is with his brother
