I saw the following sentence on Memrise website:

SINISTER forces once UNLEASHED are extremely hard to control.

The thing I can't get my head around is why we use "unleashed" in this sentence, shouldn't it be "have unleashed" or "are unleashed"

english is not my native language so can anybody explain it Thanks in advance

2 Answers 2


What happened here was shortening of a longer sentence, when the subordinate clause in a complex sentence gets abbreviated. The full sentence here was

Sinister forces, once they have been unleashed, are extremely hard to control.

But then the auxiliary verbiage of "they have been" gets dropped, since the sentence can be understood even without it.


The phrase "once unleashed" has become a standard phrase or phrasal unit. It refers to dogs unleashed meaning that once a decision has been taken it cannot be undone.

You could mean the same thing by modifying it as you describe: Once these forces have been unleashed...

I cannot see any difference between what you propose and what you have trouble with.


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