Que pasa causa ga

Who gave the famous "i have a dream" speech at the march on washington?

Pj conducts an experimental study on the effects of soft music during high stakes science testing. he randomly assigns students at the school. in one condition he does not provide music for testing while in the other group he does provide the music. he administers a pretest at the beginning of the year and a posttest at the end of the year. pj’s design is best described as a: a. static group comparisonb. pretest-posttest control group designc. control-group-time-series designd. nonrandomized control-group pretest-posttest design

Which environmental change allowed people to travel by land between asia and north america a. human apaption to arctic environments b. the introduction to horses to north america c. the formation of ice sheets on land d. a rise in ocean temperatures