Thanks for all the feedbacks.
The answer for the question raised by the last friend: No problem to buy a car even you have only a learner's licence. It's completely different story of buying a car and driving a car illegaly. I have a car with a learner's licence myself.
But be careful of driving alone. That's why I'm asking this question. We can take chance sometimes, but remember sometimes we may just unlucky.
Can Mr. Bluepoint describe a bit more about what is it look like when drunk driving. Last week when I driving, a police car just pasing by me without any problem. But still, I'm not sure whether my driving looked the same as anyone else.