The rule usually trotted out by traditional grammars regarding where to put adverbs such as the word finally, is quite complicated, and goes something like this:
- If there is no auxiliary verb, put the adverb before the main verb:
- However, if the main verb is the verb BE, then put the adverb after the verb:
- If there is an auxiliary verb and a main verb, put the adverb between the auxiliary and the main verb.
- They had finally succeded.
This can be quite tricky for students, as you might imagine. However, it gets more forbidable still, because certainly in grammar books for EFL students, it is rarely stipulated what to do when there is more than one auxiliary verb.
In modern grammars the rule can be stipulated much more simply. Modern grammars recognise auxiliary verbs as a class of verb which have similar syntactic properties, rather than verbs that come before a main verb. The verb to BE, therefore, is always an auxiliary verb, regardless of whether it is taking another verb (phrase) as its complement.
We can then simply say that:
- The adverb must be in a post-auxiliary position.
This means we can put it after any auxiliary verb. Even when there is no auxiliary we can still identify the position that we would put an auxiliary verb if it was required:
- In the end they [x] find their dinosaur.
- In the end they [do] find their dinosaur.
In such sentences the adverb goes in the post-auxiliary position:
- In the end they [finally] find their dinosaur.
From the simple rule stated in (5), we can correctly derive the following sentences where the relevant auxiliary position has been marked in bold:
- They [x] finally arrived.
- They were finally free.
- They had finally finished.
- They will finally delete them.
- They will finally be deleted.
- They will be finally deleted.
- They will finally have been deleted.
- They will have finally been deleted.
- They will have been finally deleted.