What sentence is good for isotopes?

Asupporter of slavery would respond to john brown's actions at harper's ferry with

Ball is tossed up in the air at its peak, it stops before beginning to fall.the ball at its peak has

Using mr smith and his id, identify two potential internal validity threats that might affect the a—b design. tell me how that threat might impact conclusions in the a—b design. note #1: you cannot use maturation (since i already did that one for note #2: there are some mr smith id threats that won’t have much impact in a single case design.