You may use this code:

Install and load required packages

install.packages("maps") library(maps)

Plot the map of China

map("world", regions = "China", fill = TRUE, col = "lightblue", bg = "white")

Add South China Sea

polygon(c(110, 125, 125, 110), c(10, 10, 20, 20), col = "blue", border = "blue")

Add title

title(main = "Map of China with South China Sea")

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