Tom: Hello, I would like to ask if you have a particular tropical fish I am looking for in your store
Angela: Which fish?
Tom: I need a female severum. I just have a male and I would like to give him a mate.
Angela: How big is he?
Tom: About 15 cm from the mouth to the base of the tail.
Angela: We don't have any that big, and if you put too small a female in, he will probably just chase her to death.
Tom: OK. If you do get any in, or see any, can you let me know?
Angela: OK, or what I can do is put one or two females in a side aquarium and grow them on. They will be ready in six months, but you won't find any that big in the trade, normally.
Tom: That's a great idea.
Angela: No problem, but it mean you need to pay a bit more and I need a payment in advance. Please call in tomorrow and we'll discuss it. 
Tom is looking for a female mate for his tropical fish. Angela doesn't have any specimen at the store that would be big enough to be safely put together with Tom's fish. Angela offers to grow one of the females to the required size, but it's more costly and requires a payment in advance.