Please walk into your bedroom ____ (quiet). Your father is sleeping.
①制作酸奶 ②制作米酒 ③制醋 ④生产青霉素 ⑤制作面包.
已知线段AB,延长线段AB到点C,使得BC=12AB,反向延长AC到点D,使DA=13AC,若AB=10cm,求CD的长.