three or four times ☊ 
ba bốn lần ☊ the eight festivals (beginnings of four seasons, equinoxes and solstices) ☊ bát tiết ☊ to fire four (gun)shots ☊ bắn bốn phát ☊ the four corners of the earth, the five continents, the whole world ☊ bốn biển ☊ the four oceans, the world over, the four corners of the world, all sides ☊ bốn bể ☊ four straight hours, four hours straight ☊ bốn giờ liên tục ☊ the four seasons, all year round ☊ bốn mùa ☊ the cardinal points (N,S,E,W), four directions, the four corners of the earth, everywhere ☊ bốn phương ☊ tie all four limbs ☊ trói tôm ☊ (1) four (in compound numbers) (2) private, personal
(3) capital ☊
tư ☊ (1) four (2) idea, though (in literature) ☊
tứ ☊ from four side ☊ tứ bàng ☊ the four precious writing materials (brush, ink, paper, slab) ☊ tứ bảo ☊ (all, the) four sides, everywhere, every direction ☊ tứ bề ☊ the four sufferances (birth, old age, disease, death) ☊ tứ khổ ☊ the four Chinese accents ☊ tứ thanh ☊ the four seasons ☊ tứ thời ☊ the four highest-ranking court officials in imperial Vietnam ☊ tứ trụ ☊ (of dog) white spots on the four paws ☊ tứ túc mai hoa ☊ The Four Essential Virtues ☊ tứ đức ☊ from all four corners of the world ☊ từ bốn chân trời khác nhau ☊ carriage and four horses ☊ xe tứ mã ☊