Chinese and Pakistani air force personnel sit in a Pakistani fighter after a joint drill in China, Sept 14, 2017
A photo taken on June 14, 2017 shows a poverty alleviation relocation site in Leibo county, Liangshan Yi autonomous prefecture, Southwest China's Sichuan province
（二）体现科学性和先进性，既相对稳定，又与时俱进，准确阐述本学科基本概念、基本知识和基本方法，内容选择科学适当，符合课程标准规定的知识类别、覆盖广度、难易程度等，及时反映经济社会发展新变化、科学技术进步新成果。