Find out whether there is any grammatical error in below sentence. Having learn my lessons / I was very careful / in dealing with him / in front of his room-mate.

The sentence should be: Having learned my lessons, I was very careful in dealing with him in front of his roommate.

The verb “learn” must be in the past participle form, “learned,” to agree with the subject “I.” The preposition “in” is used to indicate a location or position, and the preposition “front” is used to indicate the position of something in front of something else. In this sentence, “in front of his roommate” indicates the location of the speaker in relation to the person being spoken about.

The sentence is grammatically correct and makes sense.