A conference was held in Geneva, laying down rules for the treatment and protection of the wounded and the disaster-stricken.
Giải chi tiết:
Đáp án là A. lay down = establish: thiết lập
Các từ còn lại: cancel: hủy; đàn áp, để xuống; put inside: đặt bên trong
Around 150 B.C. the Greek astronomer Hipparchus developed a system to classify stars according to brightness.
Biogas can be utilized for electricity production, cooking, space heating, water heating and process heating.