The biggest problem I would go with foreign language and diet habit. As is known to all, the second language is a hard thing to those who want to work in another country, apparently, it is also the basic requirement of having better performance in work. But it needs time and patience. You know, Roma wasn't built in a day. Besides, local food and tradition, specifically the diet habit is equally hard to fit in life. You know, eating in a healthy way is the center of working well. Those employees who are planning to work well in foreign countries must get used to local food and tradition, undoubtedly. So, the problem could be local language and local food. That is it.