"I have lost that key."
Übersetzung:Ich habe den Schlüssel verloren.
No, that is not correct. "verloren" has to be the last word in the sentence.
- Ich habe verloren. = I have lost.
- Ich habe den Schlüssel verloren. = I have lost the key.
- Ich habe gestern den Schlüssel verloren. = I have lost the key yesterday.
See the examples. It does not matter which single words I add, "verloren" is the last word in the sentence, while "haben" as conjugated verb in a main clause(=independent clause) has to be at the second position.