明清时期我国历史最显著的特征是统一多民族国家的巩固和社会的危机。结合所学知识,回答下列问题: (1)明朝和清朝前期为抗击外国侵略维护国家主权进行了哪些斗争?各起到什么作用? ________________________________________________________________________________________________________________________________________________________________ (2)为了巩固统一多民族国家,清朝前期对新疆地区采取了哪些措施? ________________________________________________________________________________________________________________________________________________________________ (3)清朝采取了什么对外政策? ________________________________________________________________________________________________________________________________________________________________ |