How was the Third Wave developed over such a short period of time?

the figurative meanings of these lines are questioning the tyger's strength and beauty. the meaning contributes to the overall message of them poem because it is explaining how strong the tyger is.

now just elaborate off of that. : )

sentence lenght varies according to word choice.you select which word to use and that will require to use other expressions that collocate with the word chosen.sentence length will vary   according to the choice of words you make to express your ideas.