How do you know when a comma is used correctly in a sentence

Ineed passing this course. how does one listen responsively? list the exact steps needed and use interview with marielle tsukamoto as an example.

Desalination is expensive because it requires

Read this excerpt from the scarlet letter by nathaniel hawthorne and complete the sentence that follows. she had wandered, without rule or guidance, in a moral wilderness; as vast, as intricate and shadowy, as the untamed forest, amid the gloom of which they were now holding a colloquy that was to decide their fate. the author uses the point of view in the excerpt.