Why do people study a second language 人们为什么学另一门语言

Why do people study a second language 人们为什么学另一门语言
Personal interest 个人爱好; passion/ personal love 
Study another language学一门外语;study a second language; master or study 
Get to know the world in a better way 以更好的方式了解世界; in a… way
Have a deep insight into 深入了解; have a better understanding of 
Working opportunities 工作机会/job opportunities or chances 
Go on business trips 出差; go on international business trips; go on business trips all over the world