i don't understand why we must learn German?

我不明白我们为什么要学习德语。

Why do you say so? Isn't it a good thing to learn more languages?

你为什么这么说呢?多学语言不好吗?

Since English has been gradually becoming a universal language, it's useless to study other languages.

既然英语己经逐渐成为一种全球通用的语言，学习其他的语言就没用了。

No, I don't think so really. At least, when you learn another language, you can enjoy better the literature of that nation.

不，我真的不这样认为。至少，当你学习了另一种语言，你能更好地欣赏那个民族的文学。

language n.语言;措辞，说法

literature n.文学，文学作品;文献，图书资料