已知△ABC∽△DEF,△ABC比△DEF的周长比为1:3,则△ABC与△DEF的面积之比为____
已知:Ⅰ.煤气发生炉中主要反应有:
① C + O2 点燃__ CO2; ② C + H2O 高温__ CO + H2
Ⅱ.将合成的氨气部分通入碳化塔,既除去了二氧化碳又得到了化肥NH4HCO3下列说法正确的是( )
大树不会死亡。( )
Many great men were born in poor families________ Edison.