有用的表达用英语怎么表达？

　　This expression is used mainly in speech, not in writing.

　　这种表达主要用于口语，而不是书面语。

　　The course teaches students to avoid ambiguity and obscurity of expression.

　　这门课程教学生避免表达上的模棱两可、含混不清。

　　Try to put a little more expression into it!

　　尽量注入更多的感情！

　　Freedom of expression is a basic human right.

　　言论自由是基本的人权。

　　The expression in her eyes told me something was wrong.

　　她的眼神告诉我出事了。