A:夜盲症
B:地方性甲状腺肿
C:坏血病
D:镰刀型细胞贫血症
—Catherine, I have cleaned the room for you.
— Thanks. You _______ it. I could manage it myself.
将一副三角板按如图叠放,△ABC是等腰直角三角形,△BCD是有一个角为30°的直角三角形,则△AOB与△DCO的面积之比等于( )