Write your shopping list. What do you normally buy?
Pretty good, the way the list is phrased could be better, but this is fine :)
This is very good. Just need to change the end of the sentence slightly: Cereal comes in 'boxes' or the word I think you wanted was 'packets'. So I would suggest you say 'and a packet of cereal'. Packet is more of an American term. In England we tend to use 'box' more. I hope this is helpful. :)