1. According to the above description of the transaction relationship, relevant documents include invoices, packing lists and contracts, and B to C need to be displayed;

2. Whether to enjoy import tariff preference depends on the country of origin. The country of origin here is South Korea, and like the country of origin of the United States, it can enjoy most-favored-nation treatment. The certificate of origin can be directly used by the original manufacturer, namely Korea, without providing multiple invoices;

3. This may be the operation taken by B and C directly because of foreign exchange control and internal contract management;

4. The above case is a three-way transaction, but this three-way transaction is actually not typical, because B and C are essentially the same boss; The most typical three-way trade should actually be replaced by a company that has nothing to do with C. B does not handle the goods, but controls the transaction and earns the difference.