单选题 Not all member states abided by the principle they had agreed on previously.
【正确答案】 A
【答案解析】[解析] 本句意思：并非所有的成员国都遵循他们先前达成一致的原则。abide by意为“服从，遵守”，与adhere to(坚持，遵守)意思相近。abandon抛弃；apply应用；adopt采纳。