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HSK 2.0 Level 4+ HSK 3.0 Level 4+ 6 min read

Four-Character Pattern 一A一B

Use 一A一B phrases like 一模一样 and 一前一后 to say “completely, every bit” or to describe two people or things as a pair.

Pattern

一 + A + 一 + B (A and B: two related one-syllable words)

Similar A and B mean “all of it”; opposite A and B split a pair into two contrasting halves.

我家有两只狗，一大一小。

When to use Four-Character Pattern 一A一B

一A一B puts 一 before each of two one-syllable words to make a four-character phrase. If A and B are similar in meaning, the phrase stresses “whole, complete”: 一心一意 “wholeheartedly”, 一模一样 “exactly the same”. If A and B are opposites or a natural pair, it describes two people or things, one A and one B: 一大一小 “one big, one small”, 一问一答 “one asks, the other answers”.

这两张照片看起来一模一样。

These two photos look exactly the same.

他一心一意地准备考试。

He’s putting his whole heart into preparing for the exam.

上课的时候，老师和学生一问一答。

In class, the teacher asks and the students answer, back and forth.

他们俩一前一后走进了教室。

The two of them walked into the classroom one after the other.

Common traps

  • Both halves need 一: say 一大一小, not 一大小 or 大一小.
  • 一模一样 already means “exactly the same”, so don’t add 很: say 他们长得一模一样, not 他们长得很一模一样.
  • A and B must be a matching pair of one-syllable words: 一前一后 works, but 一前面一后面 does not.

Targeted drill

Practice this exact pattern before moving on.

他 地学习

He studies wholeheartedly
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