Topic: Group verb,

Best Answer Explained in Below-:

The phrase "he come --- in half an hour" requires a phrasal verb that conveys the idea of regaining consciousness or becoming alert after being unconscious. Among the options provided, "round" is the only choice that fits this context appropriately.

The phrase "come round" is a commonly used idiom that means to regain consciousness after fainting or losing awareness. For example, one might say, "After a few minutes, he came round and started to recognize his surroundings." It specifically implies a return to a state of wakefulness, making it the correct choice for this sentence.

In contrast, the other options do not carry this meaning. "Come off" generally refers to separation from something or ending an action, "come out" can imply emerging from somewhere or revealing something, and "come away" typically involves leaving a place or situation, none of which are related to regaining consciousness. Therefore, "come round" is the most suitable option that accurately conveys the intended meaning of recovering consciousness within the given timeframe.