The Progressive Theory, or the “thành ngữ tiếp diễn” in Vietnamese, is an important aspect of Vietnamese grammar. It is used to describe ongoing actions or temporary states in the present moment.

To form the progressive tense, we use the auxiliary verb “đang” followed by the main verb in the base form. For example, “tôi đang làm việc” means “I am working”, or “anh ta đang nói tiếng Anh” means “he is speaking English”.

The progressive tense can also be used to describe future plans or intentions using time phrases such as “sắp”, “sẽ”, or “đang chuẩn bị”. For instance, “tôi đang chuẩn bị đi du lịch” means “I am getting ready for a trip”, or “anh ấy sẽ đang học tập” means “he will be studying”.

The Progressive Theory allows us to provide more precise information about actions or states that are happening at a particular moment. It is a crucial concept to learn in Vietnamese grammar.