All of the following are correct English:
- Another ␣ swore to destroy it many years ago.
- Another person swore to destroy it many years ago.
- Another one swore to destroy it many years ago.
- Another one had swore to destroy it many years ago.
Native speakers of English often omit some words from their sentences.
In computer programming, these are called "default arguments."
I am not sure what language experts call them.
Consider the following:
- Joe was across the river from Sarah.
- Joe was across the river ␣.
In one case, we deleted the sentence fragment "from Sarah"
In English, we often remove certain words from our sentences if it is clear what they should be from context.
It is very common when writing computer programs. As I mentioned earlier, in computer programming they are referred to as "default arguments".
If a certain word is missing, then you are intended to assume that there is a default value.
Below is an example of an optional phrase:
- Arnold extended ␣, but Bart failed to grab the other man's hand.
- Arnold extended a hand, but Bart failed to grab the other man's hand.
Below is another example.
- Those of us ␣ lucky enough to be wealthy go to school
- Those of us who are lucky enough to be wealthy go to school
In English, you are allowed to delete a small number of words if it is clear what those words are supposed to be.