题目

My father ____ a bus to his office until the workers have had his car fixed next week. A has taken        B is taking       C had taken        D took     答案：B将一棵重约0.2公斤的柳树培育在肥沃的土壤中，两年以后连根挖出，脱水后称重达11公斤，其增加的10余公斤重量主要来源于（ ）A．土壤中的无机盐B．土壤中的无机盐和水C．大气中的氧D．大气中的二氧化碳和土壤中的水