1) Thai, because most of lao people watch thai TV and the 2 languages are not so so different 2) English, because english became the international language... usefull to communicate with most of foreigners 3) French, because of history 4) Chinese and Viatnamese because they are neighbour for Laos and many people from those countries came to Laos 5) Russian because it's was the biggest and most important communist country
Probably the simple answer is the languagee from which Lao people can get benefit for their job. That means it depends on their jobs or what language they would find jobs easily.
I am not counting Thai because it is part of the Tai dialec which Lao also belong too.
The way Lao (Thai and Camabodia) language is like the way we pronounce words, our language is perfect fit for speaking English. An ESL (English as Second Language) teacher told me one out of all his students (Chinese, Vietnamese, Japanese, Lao and Khmer) Lao and Khmer were better at pronouncing words and faster at learning the language. Chinese Vietnamese and Japanese doesn't have some alphabet or sound in their language so it is harder for them to pronounce some words. For example Chinese does not have the letter "R" sound in their language. They have hard time saying "LOCK". They would say "ROCK".
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"Because I criticized Laos government and it policies, it does not mean I want Laos to remain poor nor do I think Lao people are lazy or uneducated."