黄山是著名的旅游胜地，黄山松是一道绝世的风景，黄山松属于裸子植物，其不同于被子植物的特征是（  ）

请用化学用语填空：

（1）2个镁离子　____ ；   （2）碘酒中的溶剂分子　____ ；

（3）硝酸铵的化学式____ ；  （4）钻石的主要成分____ ．

一个人站在南极点，他的四周朝向都是（　　）

阅读理解A
    I'm Linda．I can't find my keys．I lost them this morning．There is a Lost and Found box in our classroom．My keys may (可能)be in the box．
    Oh, there are many things in the box．This is a pencil box．What color is it? It's yellow．That is a white eraser．And what's that? It is a watch．A picture of a CD is on it．It's Sara's．Wow! I find my keys．One is to my classroom，and the other (另一个)is to my house．That green cup is Jack's．This baseball is his，too．I will(将)ask him to take his things．Three rulers, two pencils and two nice pens are also in the box．Whose are they? I don't know．
根据材料内容判断正误。

剪辫、易服和停止缠足使我国社会习俗开始有较大改观，这主要应该归功于（     ）