twice as many/much用法

fancylin

看了prep笔记

有个疑问

(1)   If you say"twice as many", then this constructionshould be paired with acountable noun.
e.g., twice asmany dogs --> "dogs" is a countable noun

(2)   If you said "twice as much", then this construction should be paired with anuncountablenoun.
e.g., twice asmuch water --> "water" is an uncountable noun

(3)   If the noun in question is alreadyan explicitly numerical quantity, then you should use neither "much" nor "many". Instead, you should just use"twice" or "double" by itself.
e.g., twice theincrease --> "increase" is an explicitly numerical quantity

(4)   These rulesare followed pretty closely.
so, for instance:
twice as much water -->correct, since "water" is an uncountable noun (but is not anexplicitly numerical quantity)
twice the water... -->incorrect, since water is not a numerical quantity
twice as much as the increase... -->incorrect; redundant
twice the increase... -->correct

什么时候twice as many/much as 是正确的???

AHOLA

同问！！twice后面用一个as和两个as有什么区别？