一、旧知回顾
1.硫在空气中燃烧的现象：___________________________________________________
硫在氧气中燃烧的现象：___________________________________________________
硫在氧气中燃烧的文字表达式_________________________符号表达式_____________
2.木炭在空气中燃烧的现象：_________________________________________________
木炭在氧气中燃烧的现象：_________________________________ _______________
木炭在氧气中燃烧的文字表达式____________________符号表达式_______________
3.铁在氧气中燃烧的现象：___________________________________________________
铁在氧气中燃烧的文字表达式_____________________符号表达式_________________
4.镁条燃烧的现象:_____________ ____________________
镁条燃烧的文字表达式_______________________符号表达式__________________
