历时近4年,由薛其坤院士带领的清华大学物理系和中科院物理所组成的联合实验团队,尝试了1000多个样品,从实验上首次观测到量子反常霍尔效应。这一成果是我国科学家协同创新、集体攻关、多次试验的一个成功典范。材料蕴含的哲理是( )①实践是认识的来源②科学实验是社会存在和发展的基础③实践具有社会历史性④实践水平的提高依赖于认识的进步
I ____ to send him a telegram to congratulate him on his marriage, but I ____ it.
—It’s a long time since we met last. Haven’t you graduated from college yet? —_____. I ______ English for four years in Nanjing University.
Unluckily, when I dropped in , Dr. Smith ____, so we only had time for a few words.
—We didn’t find Smith attending the lecture. —No one ___ him about ___ a lecture the following day.
—The former president of Iraq was caught at last. —Really? Wherehimself?