Thanks Jiajin and Richard. Excuse for my ignorance, just had a quick read of He Anping's article "中国大学生英语口语 Small Words 的研究" (follow Xiaoz's post above to find it). I'm kind of against their use of "small words" to refer to "discourse markers", which is a more accepted term to many of us. As the article acknowledged, she followed Hasselgren's terminology (Hasselgren , A. 1998. Small words and Valid Testing . Unpublished PhD thesis , Bergen University , Norway.), but I still could not find convincing enough reasons why they decided to abandon the commonly used term. To make it worse, the term of "small words" is quite misleading, especially so to Chinese students.