A:H2
B:Cu
C:CO2
D:HCl
“山上多栽树,胜似修水库,有雨它能吞,无雨它能吐”,这条谚语形象说明了森林对生态环境的作用是 ( )
常温时,pH=14和pH=10的两种NaOH溶液等体积混合,所得溶液中c(H+)是( )
如果“三角”表示4xyz,“方框”表示﹣5abdc,的值.
—The American warships(军舰) have appeared near South China Sea Islands again.
—We must let the Americans know clearly that the islands ______ China.