求翻译：979年中美正式建立外交关系使得中美两国关系出现了自新中国建立以来的实质性的转变，中美关系正处于相对平稳的时期。而正如帕麦斯顿所说“国家间没有永远朋友也没有永远的敌人，只有永远的利益。”。中美两国之间因着利益问题有融洽合作，也有摩擦冲突。在当今全球化背景下，中美关系可谓是世界历史上最复杂的一对双边关系组合。中美之间变幻莫测的局势也给中美关系未来走势的研究增加了更多不确定因素。是什么意思？

979 years, China and the United States formally established diplomatic relations to make substantive changes since the New China was founded in Sino-US relations, Sino-US relations are in a relatively stable period. As Palmerston said "between countries no permanent friends and no permanent enemies,

979 years, China formally established diplomatic relations Sino-US relations between the two countries have since the founding of New China, the substantive changes in Sino-US relations are at a relatively stable period. And, as Bill Clinton, Gomez said that the inter-State is not always your friend

979-year China formally established diplomatic relations since the establishment of Sino-US relations since the new China substantive changes, is in a period of relatively stable Sino-US relations. And as pamaisidun said "no eternal friend not always enemies among States, only interests forever. ”