Americans eat ______ vegetables per person today as they did in 1990.
A:more than twice
B:as twice as many
C:twice as many as
D:more than twice as many
如图,一长方体木板上有两个洞,一个是正方形形状的,一个是圆形形状的,对于以下4种几何体,你觉得哪一种作为塞子既可以堵住圆形空洞又可以堵住方形空洞?____ (填序号).