Americans eat （ ） vegetables per person today as they did in 1996 选项A more than twice
B as twice as many Ctwice as many as希望可以说明原因
选A twice as many
解析：倍数的表达方式之一有：……倍数+as many（或much）+名词+其他+as…,所以选C
倍数表达总结：
1.用形容词表示甲是乙的几倍时,用下面三个句型,用副词表示则一般只用前两个句型.
（1）……倍数+形容词（或副词）的比较级+than
This rope is twice longer than that one．
这根绳的长度是那根绳的三倍.（比那根绳长二倍）
（2）……倍数+as+形容词（或 much）或副词+as
Asia is four times as large as Europe．
亚洲的面积是欧洲的四倍.
（3）……倍数+the size（length,height…）of
This street is four times the length of that street．
这条街是那条街的四倍长.
2.要用名词表示“量”的倍数时,则用以下两个句型：
（1）……倍数+more+名词（可数,不可数）+than
There are four times more books in our library than in yours．
我们图书馆藏书（数量）是你们图书馆藏书的四倍.（我们图书馆藏书比你们的多三倍.）
（2）……倍数+as many（或much）+名词+其他+as…
After the technique was introduced,the factory produced twice as many tractors in 1988 as the year before．
采用新的技术以后,那个工厂1988年生产的拖拉机是前一年（1987年）的两倍.（比前一年增长一倍）
