高铁酸钾K2FeO4是一种新型、高效、氧化性比Cl2更强的水处理剂，工业上常用下列反应先制高铁酸钠：2FeSO4＋6Na2O2=2Na2FeO4＋2Na2O＋2Na2SO4＋O2↑，然后在低温
如果你面向南面而站立，那么你右手所指的方向是 （ ） A、东 B、西 C、南 D、北
已知某种从太空飞船中带回的植物种子每粒成功发芽的概率都为，某植物研究所分两个小组分别独立开展该种子的发芽实验，每次实验一粒种子，假定
一Do you know the new player of our school team? 一Of course! I have never seen _______. A. a best one B. a taller one C.the tall one D. the good one
Why do children like watching TV? Many children like watching TV. It’s very interesting and they can see a lot and know many things about other people. They can learn from the radio
It’s Sunday. It’s fine. Tom does not go to school today. But he is not at home. He’s now sitting on a Chinese bus. He is going to the cinema. All his classmates will go to see a movie this after
《荀子·儒效篇》记载：“（周公）兼治天下，立七十一国，姬姓独居五十三人。”表明西周分封的主体是 A.同姓王族 B.功臣 C.先
如图，在菱形ABCD中，∠BAD＝80°，AB的垂直平分线交对角线AC于点F，E为垂足，连接DF．则∠CDF等于 ．
