What is the function of adverb clauses? Like how do u know what they modify?

Janine studies to improve her math skills

What is implied in this sentence from mark twain's "the £1,000,000 bank-note"? i was puzzled, and wanted to discuss the matter a little further, but they didn't; so i took my leave, feeling hurt and insulted to be made the butt of what was apparently some kind of a practical joke, and yet obliged to put up with it, not being in circumstances to resent affronts from rich and strong folk.

Which event occurred in the nearly two-year time span between act 3 and act4 of the tragedy of julius caesar?