Idiom: Not only X, but also Y

Howdy folks! I'd like to clear up some confusion here.

I think a lot of you are on the right track. But there are correct sentences that use this idiom and repeat the verb of a sentence, even auxillary verbs like "to be," "have," and "will." I think a lot of you are missing the subtleties of this idiom.

I found this information in the Oxford Practical English Usage book, an excellent resource for these types of questions. This is what it has to say:

"In the rather formal structure not only ... but also, not only and but also can go immediately before the words or expressions that they modify:"

• We go there not only in the winter, but also in the summer.
• The place was not only cold, but also damp.
• Not only was the bathroom flooded, but also the rest of the house.

"Mid-position with the verb is also possible. In this case, not only is generally used with do."

• She not only sings like an angel, but also dances divinely.
• She not only plays the piano, but also the violin.

These two previous cases are the reason that everyone thought that the repeated "will" was wrong. But now let's look at this last case and see why it is okay.

"Not only can be moved to the beginning of the clause for emphasis. It is then followed by an auxiliary verb + subject; do is used if there is no other auxiliary . But can be left out in this case too.

• Not only has she been late three times; she has also done no work.
• Not only do they need clothing, but they are also short of water.
• Not only will we lose our money, but we also will lose our home.

So hopefully you can see that this idiom is not as straightforward as you would like. There are some details we need to know.

Returning to the original question now: which is correct?

"The merger will not only facilitate growth, but will also provide security."

or

"The merger will not only facilitate growth, but also provide security."

According to what we just learned, the second option is preferred. If you were to see these two options on the test, choose the second since it is more concise and clear. But that does not make the first one incorrect. It is also an acceptable formulation—just not prefered.

The caveat here is that I changed the original sentence. If the original sentences were presented, what would be better?



Well in this case it is a little more sticky. It seems like the original question is incorrect version of the third case that we saw in Practical English Usage. If we write these correctly, then we can choose either to be correct:

not only will facilitate yadda yadda yadda, but will also provide me with...

OR

not only will facilitate yadda yadda yadda, but also provide me with...

Wow! That's a lot to digest. I hope that helps everyone understand this seemingly straightforward idiom.

Cheers!