Do these sentences below are parallelism? If not, what are the correct answers and WHY please?

Question

1. Not only was she noisy and rude but also rather stupid.
2. The Admiral was told he was either a liar or he was a fool.
3. The car is not only economical but also feels good to drive.

Answer 1

Neither of these sentences uses parallel structure. Parallelism means that both parts of the sentence have the same, i.e. parallel structure, e.g. if one part of the sentence has a verb in present continuous followed by an adjective and a noun, then the other part of the sentences needs the same. If it doesn't, it is not considered parallel structure. Here is an example:

Parallel structure: I am buying a green hat today, and I am selling a red car tomorrow.

Not parallel: I am buying a green hat today and will probably also sell my car.

As for your sentences, here they are but with parallel structure:

1. Not only was she noisy and rude but also stupid and belligerent. (you cannot repeat "she was" in this sentence - "not only ... but also" structure - and you need two adjectives connected with "and" to have a parallel structure)
2. The Admiral was told he was either a liar or a fool. (again, you cannot repeat "he was"; here we have two nouns; that's fine)
3. The car is not only economical but also beautiful. (two adjectives + shortened "not only ... but also" structure)

Answer 2

Here are my edited versions along with my explanations. I hope this helps.

1) She was not only noisy and rude but also rather stupid.

When using the correlative conjunction "not only...but", it's more effective (and parallel) to place the words/phrases/clauses being modified directly after the words "not only" and "but", and they should be of the same grammatical category. In the example, I placed the adjectives after "not only" and "but" to make the elements parallel.

2) The Admiral was told he was either a liar or a fool. -OR- The admiral was told either he was a liar, or he was a fool.

Similarly, after the conjunction "either", it's more effective (and parallel) for the words/phrases/clauses being conjoined to be of the same grammatical category. To fix this, we could either conjoin the adjectives (as in the first corrected example) or conjoin the clauses (as in the second corrected version). Each version has a slightly different meaning.

3) Not only is the car economical but it also feels good to drive.

In this example, in order to make the conjoined items parallel, I chose to conjoin the two independent clauses "the car is economical" and "it also feels good to drive". In the original version, the adjective "economical" was being conjoined with the clause "(it) also feels good to drive", which is not parallel.