<prompt> Translate the following text to EnglishKuna masomo ya kesi ya GAO katika maeneo mengi - makazi ya mijini, upimaji wa mifumo ya silaha, maendeleo ya jamii, mikataba ya ununuzi wa kijeshi, athari kwenye usawa wa usafirishaji na uagizaji wa Brazil, jinsi programu za kuboresha ubora wa maji zinafanya kazi, na utekelezaji wa ruzuku ya block - kutaja chache tu.  <response>: There are GAO case studies in many areas-urban housing, weapon systems testing, community development, military procurement contracts, influences on the Brazilian export-import balances, how programs aimed at improving water quality are working, and the implementation of block grants-to name only a few. 