[译] 我最好的朋友李先生住在国外已有两年了。
[误] Mr Li, my best friend, has lived in abroad for two years.

[正] Mr Li, my best friend, has lived abroad for two years.
[注] abroad 就是指 to or in another country, 前面不要加介词，所以误句中的 in 是多余的。