RON:if you say "twice as many", then this construction should be paired with a countable noun./
e.g., twice as many dogs --> "dogs" is a countable noun/

if you said "twice as much", then this construction should be paired with an uncountable noun./
e.g., twice as much water --> "water" is an uncountable noun/

if the noun in question is already an explicitly numerical quantity, then you should use neither "much" nor "many". instead, you should just use "twice" or "double" by itself./
e.g., twice the increase --> "increase" is an explicitly numerical quantity/

these rules are followed pretty closely./
so, for instance:/
twice as much water --> correct, since "water" is an uncountable noun (but is not an explicitly 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/

"the increase in X" means that X itself has increased. therefore, "the increase in the previous year" doesn't make sense, because the implication would be that the previous year itself had increased (what would that possibly mean?).

"the increase of TIME PERIOD", by contrast, means exactly what it should mean in this particular instance.

RON:if you say "twice as many", then this construction should be paired with a countable noun./
e.g., twice as many dogs --> "dogs" is a countable noun/

if you said "twice as much", then this construction should be paired with an uncountable noun./
e.g., twice as much water --> "water" is an uncountable noun/

if the noun in question is already an explicitly numerical quantity, then you should use neither "much" nor "many". instead, you should just use "twice" or "double" by itself./
e.g., twice the increase --> "increase" is an explicitly numerical quantity/

these rules are followed pretty closely./
so, for instance:/
twice as much water --> correct, since "water" is an uncountable noun (but is not an explicitly 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/

①当“非数字物体（如dogs、cats等绝大多数名词）”比较时，通常用double(twice) as much as，例如：twice as many dogs；double as much water。
②但是当带有数字概念的noun比较时，不能加as many或as much，例如：直接用twice the increase；double the decrease 就可以--排除CDE
显然地，increase本身就是数字的概念。因此，不能用as much as the increase of"

选项A（√）
The 【number 不可数名词】of flying first class on domestic flights rose sharply in 1990, 【doubling the increase of 带有数字概念的noun比较】the previous year.
1990年乘坐国内航班头等舱的人数急剧增加，比上年增加了一倍。

选项D（×）：twice as 【many（×）】 as the increase in
∵ The 【number 不可数名词】of

mark as much/many as的使用限制；
B选项the increase已经包含了the number了，无需再次用that指代！

本题涉及到了较多比较的用法。注意本题的含义，这里的double是make twice as great（造成两倍的）的意思，也就是“使increase/growth两倍”，所以本题直译过来是“今年的人数造成了去年增长人数两倍的增长”。因此，严格来讲，并不是“比较”the number of people和“去年的增长”，而是the number of people发出了“造成两倍”这个动作。

C选项：double as much as the increase of需改为double the increase of。这是因为，当“非数字物体（即，这个名词本身【没有纯粹的数字概念】，例如dogs、cats等绝大多数名词）”比较时，我们通常会用double(twice) as much as或double(twice) as many as，例如：
twice as many dogs
double as much water
但是，当“数字”比较时，我们不能加as many或as much，例如：
twice the increase
double the decrease
显然地，增长和下降本身就是数字的概念。因此，不能用double as much as the increase of。

it's so important to ascertain the meaning of the sentence FIRST, before you dive into analyzing possible errors.

the same thing is true for many other types of modifiers, such as prepositional phrases, as well.

e.g.
I read the book on the train --> this prepositional phrase modifies the ACTION "read the book".
I read the book on the table --> this prepositional phrase modifies the NOUN "book".
grammar won't help you figure this out -- you have to ascertain the meaning of the sentence using the same sort of common sense that allows you to have everyday conversations with people who don't speak using perfect grammar (i.e., everyone you will ever talk to).

modifier issues aren't really grammar issues -- they're meaning issues.
i.e., modifiers are not normally wrong because they are grammatically incorrect; they are normally wrong because they modify things that don't make sense. therefore, in most modifier errors, there is no such thing as a "proper grammar explanation" because grammar isn't even the issue in the first place.

an "appositive" vs an "absolute phrase"

you should mostly use MEANING to differentiate between the two.
for instance:
the singer sang the song with intense emotion, her voice moving the audience to tears --> absolute phrase
this is the official guide, a book containing over 800 problems --> appositive

if you think in terms of meaning, it's a rather large difference: the absolute phrase modifies the ACTION of the preceding clause, while the appositive gives more information about a THING/ENTITY/CONCEPT.

本题涉及到了较多比较的用法。注意本题的含义，这里的double是make twice as great（造成两倍的）的意思，也就是“使increase/growth两倍”，所以本题直译过来是“今年的人数造成了去年增长人数两倍的增长”。因此，严格来讲，并不是“比较”the number of people和“去年的增长”，而是the number of people发出了“造成两倍”这个动作。

选项分析：

A选项：Correct. 本选项在语法和逻辑上均是正确的。

B选项：代词that of无指代对象。在逻辑上，that不能指代the number，the increase in previous year已经表达了去年的增长数字，再用number就赘余了。

C选项：double as much as the increase of需改为double the increase of。这是因为，当“非数字物体（即，这个名词本身没有纯粹的数字概念，例如dogs、cats等绝大多数名词）”比较时，我们通常会用double(twice) as much as或double(twice) as many as，例如：
twice as many dogs
double as much water
但是，当“数字”比较时，我们不能加as many或as much，例如：
twice the increase
double the decrease
显然地，增长和下降本身就是数字的概念。因此，不能用double as much as the increase of。

D选项：本选项错误同(C)。另外，由于the number是不可数名词，所以至少应该改为much。

E选项：本选项错误同(D)。

mark ： doubling

这里的double是make twice as great（造成两倍的）的意思，也就是“使increase/growth两倍”，所以本题直译过来是“今年的人数造成了去年增长人数两倍的增长”。因此，严格来讲，并不是“比较”the number of people和“去年的增长”，而是the number of people发出了“造成两倍”这个动作。
the increase in VS the increase of

1.The number of people flying first class on domestic flights rose sharply in 1990, doubling the increase of the previous year.
这里的double是一个动词，意思是1990年的flight的增长，使前几年的增长了2倍

2.没有数字概念的名词（大多数名词都是），可数名词用 as many as;不可数名词用 as much as, 来表达数字概念
但increase, decrease这种本身就有数字含义的名词，不需要as much as来表达数字概念
所以只能说twice the increase; double the increase

1. B选项：代词that of无指代对象。在逻辑上，that不能指代the number，the increase in previous year已经表达了去年的增长数字，再用number就赘余了。
2. double as much as the increase of需改为double the increase of。这是因为，当“非数字物体（即，这个名词本身没有纯粹的数字概念，例如dogs、cats等绝大多数名词）”比较时，我们通常会用double(twice) as much as或double(twice) as many as，例如：
twice as many dogs
double as much water
但是，当“数字”比较时，我们不能加as many或as much，例如：
twice the increase
double the decrease
显然地，增长和下降本身就是数字的概念。因此，不能用double as much as the increase of。

(使)加倍;（使）增加一倍 to cause (something) to become two times as great or as many
eg. The program will double the amount of money available to help pay for child care.

as soon as you see "twice as many as the increase...", these choices are automatically incorrect (since "increase" is not a countable quantity).

1. 并不是“比较”the number of people和“去年的增长”，而是the number of people发出了“造成两倍”这个动作。

当“非数字物体（即，这个名词本身没有纯粹的数字概念，例如dogs、cats等绝大多数名词）”比较时，我们通常会用double(twice) as much as或double(twice) as many as，例如：
twice as many dogs
double as much water
但是，当“数字”比较时，我们不能加as many或as much，例如：
twice the increase
double the decrease
显然地，增长和下降本身就是数字的概念。因此，不能用double as much as the increase of。

数量增长使增长成倍。
B选项：代词that of无指代对象。在逻辑上，that不能指代the number，the increase in previous year已经表达了去年的增长数字，再用number就赘余了。

"the increase in X" means that X itself has increased. therefore, "the increase in the previous year" doesn't make sense, because the implication would be that the previous year itself had increased (what would that possibly mean?).

E. the number是不可数名词，所以至少应该改为much;
double as much as the increase of需改为double the increase of。这是因为，当“非数字物体（即，这个名词本身没有纯粹的数字概念，例如dogs、cats等绝大多数名词）”比较时，我们通常会用double(twice) as much as或double(twice) as many as，例如：
twice as many dogs
double as much water
但是，当“数字”比较时，我们不能加as many或as much，例如：
twice the increase
double the decrease
显然地，增长和下降本身就是数字的概念。因此，不能用double as much as the increase of;

"AB/CDE另一个排除法: as much as到底加不加①当“非数字物体（如dogs、cats等绝大多数名词）”比较时，通常用double(twice) as much as例如：twice as many dogs；double as much water。
②但是当带有数字概念的noun比较时，不能加as many或as much，例如：twice the increase；double the decrease。
显然地，increase本身就是数字的概念。因此，不能用as much as the increase of"