— I____ (sing) an English song now.
据新华社报道:在我国南海某海域探明可燃冰储量约有194亿立方米.194亿用科学记数法表示为( )
①NH2+CO2+X=NH4HCO3
②NH4HCO3+NaCl=NH4Cl+NaHCO3↓
③2NaHCO3 △__ Na2CO3+H2O+CO2↑
请回答下列问题: