Which organization, abbreviated CIS, replaced the USSR in 1991?

Abbey Theatre director Lady Augusta Gregory was the patron of which poet she met in 1896? Abbie Hoffman's "Yippies" took their name from which group? What is Abbott and Costello's most famous comedy routine? Which standard system of weight, based on a 16-ounce pound, is abbreviated "avdp"? Which former Soviet republic, abbreviated EST, became independent in 1991? Abbreviated GB in computer terms, what equals 1,024 megabytes? Which trade agreement, abbreviated GATT, governed world commerce from 1947? Which measurement of light is abbreviated "lm"?