JackD wrote:
what do you answer to this question: ''Anything to declare??''
Tell them what you've bought (including food, if you have) while in the other country. (e.g. "We bought some t-shirts, gifts for family, and groceries.") Typically, they will then ask if the total value exceeds a certain amount - the amount at which you'll have to pay import duties. In my experience, that's the true nature of this question - trying to find out if you need to pay import duties.
If they ask "What groceries?" then tell them, but I've not had that happen. Sometimes (much more often) they will ask if you have certain specific items, such as a specific type of fruit.
Always answer questions asked honestly, but don't answer questions that haven't been asked.