题目

下列对应化学反应的离子方程式中正确的是 A．氯气溶于水：Cl2+H2O=2H++Cl-+ClO- B．向NaAlO2溶液中通入过量的CO2：AlO2-＋4CO2＋2H2O＝Al3+＋4HCO3－ C．过量的铁和稀硝酸反应：3Fe + 2NO3- + 8H+ = 3Fe2+ + 2NO↑+ 4H2O D．NH4HCO3溶液与足量 NaOH 溶液混合：HCO3-+OH- =CO32-+H2O 答案：CIt is thought that one billion people in the world,     is half the word’s workers, earn their living by farming. A. if    B. that    C. which   D. what