zài / dà / xué / dài / shù / kè / shàng / lǎo / shī / jiè / shào / le / yǒu / lǐ / shù / yù / de / jī / běn / xìng / zhì在大学代数课上,老师介绍了有理数域的基本性质。In the university algebra class, the teacher introduced the basic properties of the field of rational numbers.