Without doing: … mà không + verb

English "without" before an action has no single word to copy. Vietnamese says the first action, then mà không and the action that didn't happen: Ảnh đi về mà không chào ai. He went home without saying goodbye to anyone (in Hà Nội, anh ấy). The order is the same as in English.

This is the mà you know as "and yet": the second action was expected, and it didn't happen. So the pattern often carries surprise or a complaint: Sao em lấy mà không hỏi chị? Why did you take it without asking me? Em ký hợp đồng mà không đọc kỹ hả? You signed the contract without reading it properly?

With không thể (can't) in front, it makes a strong rule: Không thể tới Sài Gòn mà không ăn cơm tấm. You can't come to Saigon without eating cơm tấm.

After a pause, mà is sometimes left out: Ảnh bỏ đi, không nói một lời. He walked off without a word.

When you order food or drink, plain không before the thing is enough: cà phê không đường, coffee without sugar. That's a simpler pattern of its own.