Диалог на тему: shopping используя как можно больше слова: must, could,can, should

seller: Hello. Can i help you? you: I must buy black shoes. seller: So these shoes. you: How much? seller: 20 $ you: But i only have  17 $ seller: Sorry, we couldn't help you you: But i should buy these shoes. These present for my brother. seller: So for these we can doing salle. You can buy these shoes for 17 $ you: Thank you very much. You help me. seller:  Please, come again. you: Bay, good luck.