1.viết lại câu dựa vào những từ cho sẵn kết hợp thì quá khứ đơn và quá khứ hoàn thành. 1.David had gone home before we arrived. After......................................................... 2.we had lunch then we a look around the shops. Before.................................................... 3.the light had gone out before we got out of the office. When................................................. 4.after she had explained everything clearly, we started our work. By the time..................................................... 5. my father had watered all the plants in the garden by the time my mother come home. Before...................................................