— Four students in Qingdao stood in line against a man to save a woman teacher at the school gate.
— _________ great courage they had!
A:How
B:What a
C:What
D:How a
①统一度量衡、货币
②车同轨,书同文
③焚书坑儒
④建立了统一国家
⑤开创了皇帝制、郡县制和中央集权制
⑥开创了科举制
⑦修筑万里长城、开凿灵渠
如图,⊙O中,弦AB等于半径OA,点C在优弧AB运动上,则∠ACB的度数是( )