比 sentences have one iron rule (no 很/非常/真 before the adjective) and one common illegal hybrid (不如 + 比). Both are free points if you know them. Part of the 15 high-frequency HSK 4 traps collection.
高频
9. 比 sentences cannot use 很 / 非常 / 真 before the adjective
The 比 structure already implies a degree difference. Adding a degree adverb like 很 or 非常 is redundant and ungrammatical. Use 得多 / 多了 / 一点儿 / 一些 or a specific amount instead.
✗ 他比我很高。 — 很 is forbidden after 比. The 比 structure itself signals "more than."
✓ 他比我高。 Tā bǐ wǒ gāo. — Plain comparative.
✓ 他比我高得多。 Tā bǐ wǒ gāo de duō. — Strong emphasis: "much taller."
✓ 他比我高一点儿。 Tā bǐ wǒ gāo yìdiǎnr. — Soft emphasis: "a little taller."
✓ 他比我高五厘米。 Tā bǐ wǒ gāo wǔ límǐ. — Specific amount: "5 cm taller."
Forbidden adverbs after 比: 很 / 非常 / 真 / 太 / 特别 / 有点儿 — none of them can stand between 比+B and the adjective. Same rule for 跟…一样: ✗ 他跟我一样很高 → ✓ 他跟我一样高.
不如 (bùrú, "not as good as") and 比 (bǐ, "more than") are alternative comparison structures. Each one already encodes the comparison; chaining them produces an ungrammatical sentence that test-graders mark wrong.
✗ 我的中文不如比他的好。 — Two comparison words back-to-back. Pick one.
✓ 我的中文不如他的好。 Wǒ de Zhōngwén bùrú tā de hǎo. — "My Chinese is not as good as his." (clearly inferior)
✓ 我的中文没有他的好。 Wǒ de Zhōngwén méi yǒu tā de hǎo. — Equivalent meaning, slightly more colloquial.
不如 vs 不比: 不如 = "definitely worse" (A < B). 不比 = simply "not more than" (A could be ≤ B, possibly equal). HSK 4 reading distinguishes these — 我的中文不比他的差 means my Chinese is at least as good as his, not necessarily better.
"My Chinese is not as good as his." Which is grammatical?
不如 and 比 are alternative comparison structures. Each one already encodes the comparison; chaining them is ungrammatical. Pick one or the other: 不如他的好 ✓ or 没有他的好 ✓.
