What a table! I have never seen such a thing before.It is -- it is long.

C
1. 倍数表达法中的一种:
倍数词+as+adj原级+(名词)/副词原级+as+比较对象
2. 该项答案C分别对应:否定词not+倍数词half+as wide(形容词原级) as+比较对象it is long
3.it is long相当于its length
as it is long, as在此做连词
as its length, as在此做介词

C
补充一下：
倍数的表达方法：
1）be x times the+n. of
eg；the river is 3 times the lenth of that one.
2)be x times as+adj.+as
eg:the river is 3 times as long as that one.
3)be x-1 times+adj.比较级+than
eg:the river is 2 times larger than that one.
其中x times可换为once,twice,a half.否定时在x之前+not

c

这样的桌子！我从来没见过这种长度还不及宽度的一半的桌子！