editorials:

https://www.ft.com/ft-view

非常重要的英文語法：

https://grammartips.homestead.com/possessivewithgerund.html

sed & awk GNU manual

https://www.gnu.org/software/sed/manual/

https://www.gnu.org/software/gawk/manual/

https://www.math.utah.edu/docs/info/gawk_toc.html

popular science-related

https://spaceplace.nasa.gov/laser/en/

algorithm:

https://www.programiz.com/dsa/stack

algebraic geometry

number theory

看懂費馬大猜想

https://ncts.ntu.edu.tw/scientificprograms_detail.php?gid=1&k=0

https://www.math.purdue.edu/~arapura/graph/conic.html