口语表达用英语表达是:Oral expression;
Oral:adj. 口头的; 用口的; 口腔的; 口服的; 口腔发声的。
expression:n. 表示; 表达; 表露; 表情; 神色; 词语; 措辞; 表达方式。

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I want to improve my ability of oral expression.
我想提高我的口头表达能力。
On Training the Oral expression Ability of Students in Physical Education Institute
试论体育院校大学生口头表达能力的培养
Characteristics and Significance of Body Language in Oral expression
口语表达中体态语言的特点及意义初探
The Problems and Countermeasures in the Oral expression of Rural Middle School Students
农村中学生口语表达中存在的问题与对策
Investigation on improving students' ability of oral expression
关于提高学生口头表达能力的调查