Beijing: The United States and North Korea had their first ________in four months here this afternoon as part of the ________negotiations on how to end North Korea’’s nuclear program, but diplomats played down prospects for________.James A. Kelly, assistant________, and Kim Yong II, North Korea’’s deputy foreign minister, met ________of formal discussions, ________on direct dialogue that began after a stormy meeting ________in which North Korea warned that it was moving quickly to ________nuclear arms.The Bush administration had insisted ________that it would only hold talks with North Korea ________because, it argued, only ________pressure would persuade North Korea to________. It got its way when North Korea dropped its insistence on ________and agreed, after extensive efforts by China, to hold unusual simultaneous negotiations with ________,________,________and ________as well as the United States.Though Bush administration officials had not ________talking privately with the North Koreans during________, the fact that Mr. Kelly and Mr. Kim met on the first day was seen as a sign of ________by the American side.

1687年，牛顿出版了力学经典著作《自然哲学的数学原理》，建立起一个完整的力学理论体系。其形成的历史条件包括（）①文艺复兴、宗教改革的推动②资本主义生产方式的产生和发展③新兴资产阶级的迫切需要④法国启蒙运动的推动

A.①②③

B.①③

C.②④

D.①②③④