看谁算得又对又快600-200= 300+460=530-400= 160+310=520+190= 430-270= 1000+700= 1200-400= 答案:600-200=400 300+460=760530-400=130 160+310=470 520+190=710 430-270=1601000+700=1700 1200-400=800---______ have you been in class today? ---For two hours.A.How oftenB.How longC.How manyD.How soon