I'm afraid English can not be called the most important, as most Europeans would object to it. The idea of the EU is equality within it. German is the most widely spoken mother tongue (about 88.7 million people as of 2006), followed by English, Italian, and French. However, English is by far the most spoken foreign language at over half (51%) of the EU population, with German and French following. 56% of EU citizens are able to engage in a conversation in a language other than their mother tongue. The EU has 23 official and working languages: Bulgarian, Czech, Danish, Dutch, English, Estonian, Finnish, French, German, Greek, Hungarian, Italian, Irish, Latvian, Lithuanian, Maltese, Polish, Portuguese, Romanian, Slovak, Slovene, Spanish, and Swedish. Important documents, such as legislation, are translated into EVERY official language. So, officially there is not a "most important language", as it would contradict the spirit of unity. Despite of the great role of English in the EU and in the world.

There is no single answer to this question, and each person will have a different opinion. The EU has 23 official languages, and none of them is considered to be above any other. German is the language with the most native-speakers, as well as being the language spoken in the most countries, and English is the language spoken by most people as a second language. In my travels around the EU, I have found that English is extremely useful. But this is not the case in every country. For example, English is practically useless in many parts of Spain, whilst in Italy I have always found French to be much more useful than English. Also, in Belgium and Luxembourg, I have found French to be much more useful than English. It is worth noting that elderly EU citizens, especially in Western Europe, will have been more likely to learn French or German at school than English. This situation has of course changed in the last few decades, and English is now taught as the main second language in schools in most countries throughout the Union. Nowadays therefore, whilst English, German and French are the EU’s most important lingua francas, English will likely increase in importance in most parts of the EU in the coming decades at the expense of other languages. German, however, will likely always be the most widely-spoken native language in the EU. Knowing English is useful, but being a monoglot English speaker in the EU will only get you so far. If you can speak three or four official EU languages such as any from English, French, German, Spanish and Italian, then you will surely be able to make yourself understood almost everywhere you go within the 27 member nations.

i think french in europe and english in america.

English