动 vs 了 as Potential Complements: Physical Force vs General Capacity
The potential complements 动 (dòng) and 了 (liǎo) both indicate ability, but they differ in scope. 动 focuses on whether one has enough physical strength to move something, while 了 expresses general capability to handle a situation, such as carrying multiple items or finishing a task. Choosing the wrong one can change the meaning from “can’t lift it” to “can’t manage it.”
Both 动 and 了 can be used as complements in the potential complement structure (Verb + 得/不 + complement), but they convey different kinds of inability. 动 (dòng) indicates that the subject lacks the physical strength to move or shift an object. 了 (liǎo) indicates a more general lack of capacity, often due to limitations of time, space, quantity, or overall resources. The choice between them depends on whether the obstacle is purely physical or more abstract.
When to use each
Use 动 when the inability is due to insufficient physical strength or force. It typically follows verbs of physical action like 拿 (hold/carry), 搬 (move/lift), 举 (lift), 推 (push), 拉 (pull). It indicates that the object is too heavy or requires more physical effort than the subject can exert.
动 can also be used metaphorically for 'emotional' inability, e.g., 感动 (gǎn dòng, to be moved emotionally), but as a potential complement it is strictly physical.
Use 了 when the inability is due to general capacity, such as limited time, space, or ability to manage multiple items. It can be used with a wide range of verbs, not limited to physical actions. It often implies that the action is not possible due to constraints beyond physical strength, e.g., 做不了 (cannot do it because of lack of time), 吃不了 (cannot eat because too much).
了 as a potential complement is pronounced liǎo and should not be confused with the perfective particle le. The negative form is 不了 (bù liǎo), and the positive form is 得了 (dé liǎo).
At a glance
| 动 | 了 | |
|---|---|---|
| Primary meaning | Physical inability to move something | General inability to manage or complete |
| Typical verbs | Verbs of physical exertion (拿, 搬, 举, 提) | Wider range (做, 吃, 看, 去, 装) |
| Cause of inability | Object is too heavy / requires more strength | Limited time, space, quantity, or resources |
| Example with 拿 | 拿不动 (can't lift it – too heavy) | 拿不了 (can't carry all of it – too many / hands full) |
| Positive form | 得动 (de dòng) | 得了 (dé liǎo) |
Examples
- 动这个箱子太重了，我搬不动。Zhège xiāngzi tài zhòng le, wǒ bān bù dòng.This box is too heavy, I can't move it.Physical strength insufficient to lift/move the box.
- 动他举得动一百公斤的杠铃。Tā jǔ de dòng yī bǎi gōngjīn de gànglíng.He can lift a 100 kg barbell.Positive example: he has the physical strength.
- 了今天事情太多了，我做不了。Jīntiān shìqing tài duō le, wǒ zuò bù liǎo.There's too much to do today, I can't manage it.General capacity: too many tasks, not enough time.
- 了这些菜太多了，我吃不了。Zhèxiē cài tài duō le, wǒ chī bù liǎo.There's too much food, I can't eat it all.Quantity too large; not about physical strength.
- 动他拿不动那个大石头。Tā ná bù dòng nàge dà shítou.He can't lift that big stone (it's too heavy).Use 动 because the obstacle is weight.
- 了他拿不了那么多东西。Tā ná bù liǎo nàme duō dōngxi.He can't carry so many things (hands full / too many).Use 了 because the obstacle is quantity, not weight.
Common mistakes
- Using 了 (liǎo) when the inability is purely due to physical weakness – e.g., saying 拿不了 for a single heavy object; use 拿不动.
- Using 动 (dòng) for general capacity issues like time constraints – e.g., saying 做不动 when you mean 'can't do it because of other commitments'; use 做不了.
- Pronouncing 不了 as 'bùle' instead of 'bù liǎo' in potential complement contexts.
- Confusing 了 as a potential complement (liǎo) with the perfective particle le – e.g., writing 吃了不聊* (gibberish) instead of 吃不了 (bù liǎo).
FAQ
- When do I use 动 vs 了 as a potential complement?
- Use 动 when the inability is due to insufficient physical strength (e.g., an object is too heavy to lift). Use 了 when the inability is due to general capacity, such as too many items, not enough time, or other constraints beyond pure physical force.
- Can the same verb take both 动 and 了? What's the difference?
- Yes, for example, 拿不动 means 'can't lift it (because it's too heavy)', while 拿不了 means 'can't carry it (because there are too many items or hands are full)'. The choice changes the reason for the inability.
- How do I pronounce 了 in potential complements?
- It is pronounced liǎo (third tone), not le. The positive form is 得了 (dé liǎo), and the negative is 不了 (bù liǎo). Do not confuse it with the perfective particle le.
- Is 动 always about physical strength?
- As a potential complement, yes – 动 indicates the ability to move something physically. However, 动 has other unrelated meanings (e.g., 感动 'to be emotionally moved'), so context is important.