While having a conversation, my friend said 'I almost completed...', but when I heard that line, it sounded to me like 'I nearly did something, which I should not have done, and thank god for that' although what he actually meant was he had little work left to do then. Am I missing something? Or is 'I almost completed...' grammatically incorrect?
I almost completed
Indicates an action in the past, which you were doing, and is all gone now. So you say "I almost completed the running race, but had to stop half-way through."
I have almost completed
Means something is still ongoing, and you expect to finish soon. "I have almost completed the race, there are only 500m to go."
(The tense names give these two away - "almost completed" is past tense, "have almost completed" is present perfect.)