In what places did mesopotamia became the center of civilization?

What is the purpose of the system of checks and balances

Which of the following was used only once, to ratify the 21st amendment (repealing prohibition)? a.three-fourths of both houses of congress. b.three-fourths of the state legislature approved it. c.two-thirds of the state legislature approved it. d.ratifying conventions in three-fourths of the states approve it.

If one thinks illegal immigrants should become american citizens, should they become american citizens automatically or should there be a waiting period?