有一句话:The factory has turned out twice as many TV sets this year as last year.
这里twice就是前位限定词,many就是后位限定词?

第一，其实你所举出的习题是不需要根据限定词类型的语法规则就能做出来的，应当根据英语中倍数的表达法进行选择。

倍数的表达法：
1）倍数 + as + adj. + as ...
2）倍数 + 形容词比较级 + than ...
3）倍数 + the + size/length等名词 + of ...

第二，根据你的要求，我将相关知识罗列如下：

按其不同的搭配位置，限定词可分为：
1〕中位、前位、后位限定词
按照限定词与限定词之间不同搭配位置，限定词可分为中位限定词（CENTRAL DETERMINER〕、前位限定词（PREDETERMINER〕和后位限定词（POSTDETERMINER〕。
a) 中位限定词包括a(n), the, zero; this, that, these, those; my, your, etc; Merry's, my friend's; some, any, no, every, each, either, neither, enough; what(ever), which(ever), whose等
b) 前位限定词包括all, both, half; double, twice, three times, etc; one-third, two-fifths, etc; what, such, (a / an)等
c) 后位限定词包括one, two, three, etc; first, second, third, etc; next, last, other, another, etc; many, much, (a) few, (a) little, fewer, (the) fewest, less, (the) least, more, most; several, plenty of, a lot of, lots of, a great / large / good number of, a great / good deal of, a large / small amount of; such等
2) 三类限定词的搭配关系
如果一个名词词组带有上述三类限定词，其搭配关系总是按照"前位－－中位－－后位"的顺序排列。例如：
all前the中four后teachers.
all前your中three后books.
all前these中last后few后days.
如果只有上述两类限定词，其搭配关系仍按上述顺序。例如：
half前his中lecture.
those中last后few后months.
several后hundred后guests.
all前other后students.
such前a中misfortune.
some中such后alloy.
由上述诸例可以看出，中位限定词之间和前位限定词之间是互相排拆的，即一个名词中心词之前不可并用两个中位限定词或两个前位限定词。所以，"我的那本书"不是* my that book而是that book of mine，因为my和that同是中位限定词，不可同时并列。但后位限定词的使用却不受此限。除上述those last few months, several hundred guests之外, this last two books, the first two chapters, three other girls, two more sheets, the next few weeks, many more copies, a few more samples, another twenty tons等都是后镁限定词重叠使用的实例。
个别限定词有跨类现象，如such既属于前位限定词，又可归入后位限定词。由于它只是在such a...和such an...这样的搭配中属于前位限定词，而在与其他限定词(some, any, no, all, few, another, other, many, one, two, etc)搭配时，such则是后位限定词，一律放在上述这些限定词的后面，如some such, any such, nosuch, few such, one such等，因此本书把它归入后位限定词。