What time does Grace want to play volleyball?
A:At 5:00 p.m.
B:At 5:30 p.m.
C:At 6:00 p.m.
本市公共场所已全面实施禁烟。香烟烟雾中易与血红蛋白结合的物质是( )
下列有关氧气的说法不正确的是( )