I am learning about definite articles. I came across a thread: Definite article: "use ‘the’ with names" vs "use ‘the’ with the names"
That says "the" is optional in these general sentences below:
[The] leaders of democratic nations are usually persuasive public speakers. [The] shorelines of lakes are sometimes highly developed. [The] covers of graphic novels often feature a dramatic scene from the story.
If so, when talking about a type of something in general, I can use either version. Right? Could you tell me the subtle difference between the version with "the" and without "the" of sentences above?
As I can see, the examples above talks about plural noun (leaders, shorelines, covers, . I also wonder if this can applies with uncountable noun when making a general statement. Is "the" also optional in these sentence below:
(The) development of cities has become the first concern for governments in the word.
(The) contamination of water has become severe nowadays.