A. AT FIRST B. AT BEGINNING C. AT STARTING D. AT FIRST TIME

5. - MO SO BAI TAP DOC HIEU VA TRA LOI CAU HOI TIENGANH LOP 9
MO SO BAI TAP DOC HIEU VA TRA LOI CAU HOI TIENGANH LOP 9

5. A. At first B. At beginning C. At starting D. At first time