Knowing the customer's needs. Try to guess, that the reason why he would not buy because of what. Students must find a way off, sales channels and find a way to sell products.
Understand customer Try to guess whether customers. The reason why he will not buy. The seller also must find a way to close the channel. And find a way to sell it eventually.
Know the needs of customers. Trying to figure out what customers The reason why he won't buy it. Sales need to hurry up and find them. And find a way to sell products to the end.