— _____ are they from?
—They are from Tokyo.
— “What are you doing?“asked Mom.
— “I am watering flowers,” responded Jack.
如图，在圆心角为直角的扇形OAB中，分别以OA，OB为直径作两个半圆，在扇形OAB内随机取一点，则此点取自阴影部分的概率是____．
