A:①②
B:③④
C:①③
D:②④
如图,点A、B、C都在圆O上,若∠AOB=68°,则∠ACB的度数为( )
Panama,____ country in Central America, is the only place in the world ____ someone can see the sun rise on the Pacific Ocean and set on the Atlantic.
如图,点C是半径为2的圆的劣弧AB∧的中点,连接AC并延长到点D,使得CD=AC,连接DB并延长交圆于点E,若AC=2,则AC→•AE→的值为____
_______he had failed many times, he didn't give up and succeeded in the end.