Are these sentence fragments or phrases ? What is the distinction between the two as phrases don't always have subjects either. Online examples have some some subordinate clauses as 'fragments' whilst others just have groups of words that look like sentences as a definition. (rained all night).
They don't grammatically comprise a complete thought but they convey one and we'd used them alone in speech.
hit a nerve
keep it safe
let yourself in
find the keys to the door
useless detective can't catch the criminals.
find out who else can take care of the dog.
assume his identity is real
Most of those you listed are sentences in the imperative mood. They would be sentences if you add ending punctuation and capitalize the first letter. These are fragments because the thought is incomplete due to missing elements (added in red): That useless detective can't catch the criminals.
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Most of those you listed are sentences in the imperative mood. They would be sentences if you add ending punctuation and capitalize the first letter.
These are fragments because the thought is incomplete due to missing elements (added in red):
That useless detective can't catch the criminals.
The dentis