I have a question about a sentence:
Lost in thought, he almost ran into the car in front of him.
Why, in this sentence, do we need to use 'lost' instead of 'losing'? In my understanding, 'he', is active to think about something. Except that, the verb is placed at the beginning of the sentence.
"Lost" works as an adjective. The structure of the expression is "to be lost in thought"; the verb in the expression, then, is the verb "to be". In your sentence, the verb "to be" is omitted but inferred: "When he was lost in thought, he almost ran into the car in front of him".
We use the verb "to lose" usually followed by an object (a hat, a game, a book...). Here, "thoughts" are seen as a metaphorical place. When we are thinking, we are in our thoughts. You cannot lose a place; it is you who get lost when you are in that place. It is necessary to use the adjective "lost" to describe the state of the person. The verb can be used in this kind of case to talk about losing the thoughts themselves: "I lost my train of thoughts".
