Good one

[hpgmat]

the number of people flying first class on domestic flights rose sharply in 1990, doulbling the increase of the previous year.

A - doulbling the increase of
B-doubling that of the increase in
C- double as much as the increase of
D- twice as many as the increase in
E-twice as many as the increase of

what is actually being tested here ? please explain your answer

[heshamelaziry]

the number of people flying first class on domestic flights rose sharply in 1990, doulbling the increase of the previous year.

A - doulbling the increase of
B-doubling that of the increase in
C- double as much as the increase of
D- twice as many as the increase in
E-twice as many as the increase of

what is actually being tested here ? please explain your answer

B is awkward.
C is awkward and doesn't make sense too
D should be twice as many passengers flew as in the previous year.
E same wrong usage of many with increase.

A IMO is correct because a verb ending with "ing" after a comma can modify the sentence before the comma.

[hpgmat]

which is idiomatic ?
twice as many or twice as much
double as many or double as much

thanx

[heshamelaziry]

IMO twice as many passengers, and twice as much sugar. Double as many is not idiomatic.