If you look up 肯定 (kěndìng), 确定 (quèdìng) and 一定 (yīdìng) in the dictionary, they all have similar meanings, like "certain" or "surely." However, using them correctly in a sentence is a bit more complicated.
Overview 概述
So how are these three words words different? We can answer this question from two points of view:
1. From a "parts of speech" point of view:
- 肯定 can be a verb, an adjective and an adverb.
- 确定 can be a verb or an adjective.
- 一定 can be an adjective or an adverb.
2. From a "significance or meaning" point of view:
- 肯定 often has a subjective, energetic feel to it. It carries meanings like 认可 (approval), 同意 (agreement), and 保证 (guarantee).
- 确定 carries a feeling of objectively describing a situation. It carries the meaning of 决定 (to decide, to resolve).
- 一定 as an adjective has really broad uses, so you need to pay attention to the specific times it's used in. As an adverb, it is often used to give a reinforcing tone.
- 肯定 and 确定 can both be verbs, but their use and meanings are different. 一定 cannot be used as a verb.
"肯定" and "确定" as a Verb
Structure with 肯定
肯定 can express that something is satisfactory (对…满意), often used when a superior evaluates subordinates. When used this way, it should be followed directly by a noun or a phrase that is acting as a noun (noun phrase).
I can also be used to express "I am sure." When used this way it is usually a clause at the end of a sentence.
Subj. + (敢)肯定 + Sentences
Examples with 肯定
- 老板 肯定 了 我们 团队 的 工作。 The boss approved our team's work.
- 如果 想 让 别人 肯定 你，你 就 要 好好 做。 If you want to make other people like you, you have to do good work.
- 我 敢 肯定 这 就 是 他 的 声音。 I'm sure that this is his voice.
Structure with 确定
You can also add a verb phrase a preposition phrase after 确定, which makes it mean that that something is already set, often used in describing a progressing condition.
Examples with 确定
- 我们 还 没有 确定 什么 时候 开始。 We still haven't decided when to start.
- 已经 确定了 三 个 人，还 差 一 个。 Three people have already been decided, one more is needed.
- 你 确定 他 是 我们 要 找 的 人 吗？ Have you decided if he's the person we'll look for?
Examples of right or wrong sentences
- 我们 要 先 肯定 一 个 形式 才 能 开始 做。 In this sentence, "肯定" needs to be followed by a noun or a noun phrase.
- 我们 要 先 确定 一 个 形式 才 能 开始 做。 We'll have to decide on a design before we can start working.
- 老板 肯定 了 最近 我 工作 很 努力。 In this sentence, "肯定" needs to be followed by a noun or noun phrase.
- 老板 肯定 了 最近 我 的 努力 工作。 By changing the word order, we get a noun phrase instead of a verb phrase.The boss approved my recent hard work.
"肯定" "一定" as an Adverb
肯定 and 一定 can both be adverbs, and the grammar structure for both are similar. 肯定 emphasized more of a subjective judgement or promise. 一定 sometimes carries an air of forcing something or issuing a command.
Structure with 肯定
Examples with 肯定
- 他 肯定 还 没 起床，因为 他 的 手机 现在 还 没 开 机。 He definitely hasn't gotten out of bed yet， because his phone is still off.
- 这 次 我 肯定 不 骗 你，骗 你 是 小 狗，好 吧？ The idiom "骗你是小狗" literally means "To deceive you is to be a small dog." It doesn't have a good English equivalent. I'm not lying this time. Cross my heart.
Structure with 一定
Examples with 一定
- 明天 你们 一定 要 来。 You guys are definitely going to come tomorrow.
- 一定 要 小心。 You've definitely got to be careful.
Right or Wrong
- 你们 肯定 要 去 听 我 的 演唱会。 Since it's a command, "肯定" is not appropriate.
- 你们 一定 要 去 听 我 的 演唱会。 You guys have to go listen to my music recital.
"肯定" "确定" "一定" as as Adjectives
All three of these can be placed before a noun as adjectives. But in this grammar structure, 肯定 and 确定 use their verb meanings, and 一定 as an adjective means "something particular
Structures
Examples
- 如果 你 问 我 是不是 知道 这 件 事情，我 的 回答 是 肯定 的。 If you ask me if I know about this, my answer will be sure.
- 请 给 我 一 个 确定 的 回答，不 要 总是 这么 模糊。 Please give me a definite response. Don't always be so vague.
- 我们 之间 要 保持 一定 距离。 We need to keep a certain distance between us.
- 这 件 事 和 他 有 一定 的 关系，不 能 都 怪 你。 He has a certain connection with this, it can't completely surprise you.
See Also
Sources and further reading
Books
- 对外汉语教学语法释疑201例 (肯定 vs 一定 p.180)
Dictionaries
- 现代汉语词典（第5版） (肯定p.776 一定 p.1594 确定p.1136)