氧气的用途：______，______．
氧气具有助燃性，能跟许多物质发生氧化反应，故氧气的用途有支持燃烧，供给呼吸．、
故答案为：供给呼吸，支持燃烧．
用方框中所给单词的适当形式填空，每个单词限用一次。
小题1:I haven’t seen my cat for two days. I’m very________ about her.
小题2:The old should be spoken to ______.
小题3:Don’t make so much __________. Your father is sleeping in the next room.
小题4:I only just ________ the bus to school when I got to the station yesterday.
小题5:_________ of people got hurt in the Shanghai’s big fire (火).
本导则中规定；大气环境影响一级评价范围，距离风险源点不低于( )。
A．2km B．3km C．4km D．5km
