Adjective reduplication: 高高的, 干干净净
形容词重叠 / adjective reduplication
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
AA + 的 / AABB + 的
Reduplicating an adjective makes it more vivid and descriptive, often affectionate: 大大的眼睛 (big eyes), 长长的头发 (long hair).
1 syllable: AA + 的 (高高的, 红红的). 2 syllables: AABB (干干净净, 高高兴兴, 漂漂亮亮).
Reduplication already carries intensity: add no 很 or 非常, and don't negate it.
Examples
她有一双大大的眼睛。
Tā yǒu yì shuāng dàdà de yǎnjing.She has big eyes.
我妹妹的头发长长的。
Wǒ mèimei de tóufa chángcháng de.My little sister's hair is long.
孩子们高高兴兴地回家了。
Háizimen gāogāoxìngxìng de huí jiā le.The kids went home happily.
房间打扫得干干净净的。
Fángjiān dǎsǎo de gāngānjìngjìng de.The room has been cleaned spotless.
Common mistakes
✗ 很高高的 → ✓ 高高的.
✗ 干净干净 → ✓ 干干净净 (AABB for adjectives, ABAB for verbs).
✗ 不高高的 → ✓ 不高.