The nice site I have found today is certainly one of the best on English expressions. The Phrase Finder is simple to look up and efficient. It also shows the origins of what makes its entries.
www. phrases.org.uk
Do not be suspicious about the 'uk' in the URL. The once so much talked-about difference between British and American English is still an issue only for those who did not catch up with the times - at least as far as English is concerned. Of course there are differences, but they are unimportant for those really engaged in learning the language to communicate globally. Getting rid of the vicious 'method' of constantly thinking in Portuguese before trying to speak in English is the most crucial thing to do.
