同一个圆的内接正六边形与其外切正六边形的周长比是（ ），面积比是（ ）。
；3∶4
—I would like to buy an expensive camera.
—Well, we have several models________.
A．to choose from
B．to choose
C．to be chosen
D．for choice
有甜味的生物碱是( )
A．烟碱 B．麻黄碱 C．川芎嗪 D．小檗碱 E．甜菜碱
；3∶4
；3∶4