1 los chicos calleron 2 el profesor cree
Should/must
Deber means that you should/must do something
Yo-voy
ella (and) èl-va
Tú-vas
nosotros-vamos
ellos-van
Answer: Differences: Costumes, in U.S. celebrate his costumes like the independence day 4 of July. In Ecuador Costumes are the 24 of May war. In South America used to make their own medicines with the nature, while in the United States make with diferent types of chemical process in the drugs.
Similarities: Celebrate New year, Christmas and have the same thinking of the science.
Explanation: I think that the answer says all you need to know and this question isn't from spanish, it's from geography.
