Hearing this, seeing that: a verb phrase before the subject (Nghe tin, cô ấy khóc)

Vietnamese can open a sentence with a short verb phrase and no linking word: Nghe tin, cô ấy khóc. Hearing the news, she cried. The first action happens just before the second, or it's the reason for it, and the same person does both. English uses an -ing phrase or "when"; Vietnamese simply puts the verb phrase first, then a comma, the subject and the main verb.

Thấy (see, notice) is the most common opener, and a whole sentence can follow it: Thấy trời mưa, tôi ở nhà luôn. Seeing it was raining, I just stayed home. The one who sees is still the subject after the comma: Thấy mẹ về, thằng nhỏ chạy ra cửa. Other everyday openers are nghe (hear), về tới nhà (getting home) and a verb with xong (finished): Ăn cơm xong, tụi mình đi coi phim nha.

To show the second action came at once, add liền (right away). In stories it goes before the second verb, liền chạy ra; in Saigon speech it more often comes at the end, chạy ra liền.

News reports use the pattern all the time: Nhận được tin báo, lực lượng cứu hộ … On receiving the report, the rescue team …

Khi (when) and sau khi (after) say the link outright: Khi nghe tin, cô ấy khóc means the same, a little more spelled out. The bare verb phrase is tighter, and it suggests the second action follows directly from the first. Keep the opener short; a long one reads better with khi or sau khi.