来自刘纪远的问题
指出下列符号的意义N__________、_________;2N___________、___________;N2__________、__________.指出下列符号的意义N_____________、______________;2N_____________、_______________;N2_______________、_____________.空气的
指出下列符号的意义N__________、_________;2N___________、___________;N2__________、__________.
指出下列符号的意义N_____________、______________;2N_____________、_______________;N2_______________、_____________.
空气的成分按体积计算,约占78%的物质名称是____________.
1回答
2020-03-06 09:45