— They are playing basketball.
A：What are they doing
B：What do they do
C：How are they
D：Where are they playing
①铁能被磁铁吸引，但纯铁易锈蚀
②在人体的血红蛋白中含有铁元素
③不能通过化合反应生成FeCl2和Fe（OH）3
④铁能在氧气中剧烈燃烧，但不能在水蒸气中燃烧
⑤铁与硝酸反应的产物仅是Fe（NO3）3．
