The students have collected three materials and intend to choose two of them to put in the same column. Which two do you think should be chosen? Why? Please combine again.

Example 1: Choose one or three materials, because the contents of these two materials are: overcoming difficulties in the field of science and technology in China, independent research and brilliant achievements. Column name: self-reliance (or self-improvement), create brilliance together;

Choose one or two materials, because the contents of these two materials are: In the research of nuclear weapons, China's scientific and technological personnel successfully developed nuclear weapons without foreign aid, and surpassed the world powers in speed. Column name: self-reliance (or self-improvement), catching up with big countries.