I want to take Air China from Qingdao to Los Angeles via Beijing

It depends on your cabin. If you have an economy class student ticket, you can generally apply for a checked baggage of 30kg to 40kg. If it is overweight, there is generally no fine if it is less than 5kg. If you have a carry-on baggage, the requirement is only one piece of 5kg, but In fact, you can bring a small suitcase and a small travel bag as long as the weight can fit in the luggage rack. No one cares. Scissors can only be placed in checked luggage. I recommend putting liquids in checked luggage. As for food, there are no strict restrictions in China. However, if you are abroad, some vegetables, fruits, meat, dairy products, etc. are prohibited from entry. You have to check the details in the United States