is this parallelism grammatically correct?

Question

does this sentence make sense "One of the reasons why spoken English teaching in China seems to be not really successful is not only because students lack of enthusiasm, but their teachers as well" when it comes to parallelism?

Answer 1

I am afraid the sentence is poorly written. It would be more intelligible if you said

One of the reasons why spoken English teaching in China does not seem to be very successful is because not only students lack enthusiasm, but their teachers (do) as well.

Cambridge explains that we can omit also in this structure:

Not only … but also
We use not only X but also Y in formal contexts:

The war caused not only destruction and death but also generations of hatred between the two communities.

We can sometimes leave out also:

I identified with Denzel Washington not only as an actor but as a person.

Also of course is a synonym of as well (and in the writing of the sentence the structure is not only... but... as well), but as you can see in the comments they are not used in the same way.

TheWordCounter shows that there are other variations:

Variations on Not Only / But Also
Sometimes the phrase “not only” can be replaced by “not alone” or “not just.” Similarly, “also,” “but too,” and but as well” can be good substitutes for “but also.”

Not only was he strong, but he was smart as well.

not just…but also
not only…also
not only…but too
not only…but as well
not alone…but also

With also your sentence would be:

One of the reasons why spoken English teaching in China does not seem to be very successful is because not only students but also teachers lack enthusiasm.

Answer 2

While using 'not only...but also', the nature of what follows immediately after 'not only' should match with that of 'but also'. Thus it may be rewritten as "One of the reasons why spoken English teaching in China seems to be not really successful is because of the lack of enthusiasm not only of students but also their teachers." But the sentence, I should tell, is too wordy.

Answer 3

"Reason" and "because" cannot be used together. These are redundant.

"The reason for my absence was because of my illness." This is incorrect.

Here, the correct sentence should be :

" The reason for my absence was my illness." Or, "My absence was because of my illness (or, due to my illness)."

Besides, "the reasons why" also seems to be redundant. It's better to say : "the reasons for which"...

Therefore, the correct version of your example is :

"One of the reasons for which spoken English teaching in China seems to be not really successful is the lack of enthusiasm not only of the students but also of their teachers."

Or,

"Spoken English teaching in China seems to be not really successful because of the lack of enthusiasm not only of the students but also of their teachers."