基石

foundation stone;cornerstone;keystone;bedrock;anchor
加强同第三世界国家的团结与合作，是中国对外政策的～。It is the cornerstone of China’s foreign policy to strengthen its unity and cooperation with other Third World countries./大西洋联盟一直是美国政策的～。Atlantic alliance remains the keystone of US policy./教育是中国发展的～。Education is the bedrock of China’s development.