TOEFL ITP (Test of English as a Foreign Language: Institutional Testing Program) is now used as part of the test format designed by Vietnam National Foreign Language Project 2020 to test the English proficiency of Vietnamese. However, they tend to do poorly in the listening comprehension section of the tests of the Project, in which short conversations between two people in part A are the first challenge. Besides the high speaking speed of the native speakers in the recordings, the grammatical structures that convey the meaning of each conversation seem to be one of the linguistic components affecting the students' understanding of each conversation. Realizing the students' problem above, the author have conducted an analysis of clause expansion in three selected short conversations consisting of requests and their responses in part A of the listening comprehension scripts of the book "TOEFL Preparation Kit Workbook 2002-2003, Volume I" designed and introduced by ETS, in light of Systemic Functional Grammar. The results of the analysis suggest further studies on more conversations of this kind.