英语翻译1：他们发现要掌握一门外语是困难的.2：这项研究表明成功人士在许多方面是相似的.3：成功的语言学习者不止依赖课本或是老师.

They found it hard to master a foreign language
The research shows that successful people are similar in many ways
Successful language learners do not rely on textbooks or teacher