Comparing "turan" and "huran"

Both 突然 and 忽然 express the something happens in a very short time or is unexpected. Both can be translated as "unexpectedly" or "surprisingly", however, 突然 is a bit harsher in tone while 忽然 is a bit softer. Also, their grammatical structures could be different, as outlined in this article.

Both can be used as adverbs or as adjectives

突然 and 忽然 both can put in the sentence as adverbs or adjectives, just make sure to put them before the verb or the adjective!

Structure as adverb

突然/忽然 + Verb

Examples

• 睡觉 的 时候，我 的 电话突然 响了。
• 睡觉 的 时候，我 的 电话忽然 响了。
• While I was sleeping, my phone suddenly started to ring.
• 他 说着说着突然 不 说 了。
• 他 说着说着忽然 不 说 了。
• He was talking and talking, and suddenly stopped.

Structure for Adjective

突然/忽然 + Adjective

Examples

• 天 突然 暗 了。
• 天 忽然 暗 了。
• The sky suddenly got dark.
• 灯 突然 不 亮 了。
• 灯 忽然 不 亮 了。
• The lights suddenly went out

Both can be used at the beginning of a sentence

You can place 突然 and 忽然 at the beginning of a sentence, just make sure to add a comma after it!

Structure

突然/忽然，...

Examples

• 突然，他 进来 了。
• 忽然，他 进来 了。
• Suddenly, he entered.

突然 can be used as an adjective

突然 can be used as an adjective, while 忽然 cannot. In order to use 突然 as an adjective, place it in front of the verb.

Structure for adjective

突然 + （的）+ Noun

Examples

• 这 是 一 场 突然 事故，我们 都 没 想 到。This was a sudden accident. None of us thought it could happen.
• 你 知道 怎么 处理 这 种 突然 的 情况 吗？Do you know how to handle this kind of sudden situation?

突然 can be used as a complement

突然 as an adjective can also be sued as a complement (called 补语 in Chinese). 忽然 cannot be used as a complement.

Structure for verb and complement

Subject + Verb + 得 + 突然

Examples

• 事情 发生 得 太 突然，我们 不 知道 怎么 办。Things happened so suddenly, we didn't know what to do.
• 这 场 雨 下 得 太 突然，都 淋湿 了。This rain fell so suddenly, everything got soaked.

突然 can be used as the predicate

Just like other adjectives, 突然 can be used as the predicate of a sentence. It is usually added with a modifier like 很, 非常, 不 etc. It can also end with 得很, 得多, 极了, etc. complements.

Structure with modifier + 突然

Subject + modifier + 突然

Examples

• 这 个 决定 太 突然 了。This decision was too sudden.
• 对 她 来说，这 次 升职 其实 不 突然。To her, this promotion wasn't actually surprising.

Structure with 突然 + modifier

Subject + 突然 + modifier

Examples

• 离开 上海 突然 得 很。Leaving Shanghai is really surprising.
• 这 次 生病 比 上 次 突然 得 多。Getting sick this time is much more surprising than the last time.

Example of right and wrong sentences

• 这 个 决定 很 忽然。
• 这 个 决定 很 突然。
• 一切 发生 得 太 忽然。
• 一切 发生 得 太 突然。

Example Dialog

• A: 我 正在 睡觉，忽然 电话响了，是 Amy 打 来 的。
• B: 她 说 什么？
• A: 她 结婚 了。
• B: 啊，这 个 消息 太突然 了。

Sources and further reading

Books

• 现代汉语八百词（增订本） (突然 p.540) →buy

• 现代汉语虚词例释 (忽然p.247)→buy

• Chinese Grammar - Broken down into 100 items - Basic and Intermediate Levels (汉语语法百项讲练 - 初中级) (section)(突然 忽然p.113)→buy

Dictionaries

• 现代汉语词典（第5版） (忽然p.574 突然p.1378) →buy

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