@Setanta,
Spanish is spoken by many millions of people in the western hemisphere, as well as in Spain
. French is spoken by many millions of people in Africa, as well as in Europe (France, Belgium, Switzerland)
. German is not as widely spoken, but it is a language of business
, industry and scientific and technical journals, but i don't know if you would have any use for that
. Japanese makes sense for business reasons; Korean arguably makes sense for business reasons, although much less so
. Japanese and Korean, by the way, are Altaic languages, and are not similar to Chinese
.Russian might be useful, just because it was the language of hundreds of millions of people in the days of the Soviet Union.
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It should be: German, Japanese, France, Chinsese, Spain. You can go all over the world with these languages. But I think you will be so old to do that