juānzèng jiùwù kěyǐ téngchū kōngjiān.

The structure is:

捐赠旧物 + 可以 + 腾出空间

That is:

• 捐赠旧物 = donating old items
• 可以 = can / is able to
• 腾出空间 = free up space

So the whole sentence means something like:

Donating old items can free up space.

In Chinese, this kind of sentence often uses a verb phrase as the subject/topic, so 捐赠旧物 functions like donating old things in English.

Yes. In this sentence, 捐赠旧物 acts like the subject.

Chinese can use a verb-object phrase as the subject of a sentence. So:

• 捐赠 = to donate
• 旧物 = old items / used things
• 捐赠旧物 = donating old items

This is similar to English sentences like:

• Recycling helps the environment.
• Exercising improves your health.

So 捐赠旧物可以腾出空间 is structurally similar to Donating old items can free up space.

捐赠 means to donate, usually in a somewhat formal or neutral way.

• 捐 by itself can also mean to donate, but it is shorter and often used in compounds.
• 捐赠 sounds a bit more complete and standard in formal writing or public messages.

For example:

• 捐衣服 = donate clothes
• 捐款 = donate money
• 捐赠旧物 = donate used items

So 捐赠 and 捐 are related, but 捐赠 is often a little more formal.

旧物 means old items, used belongings, or secondhand things.

• 旧 = old, used
• 物 = thing, object

Compared with 旧东西:

• 旧物 sounds a bit more concise and slightly more written or formal
• 旧东西 is more conversational and everyday

So both can work, but 旧物 fits well in a short written sentence like this, especially in posters, notices, or advice.

Because 旧物 is a fixed-style noun phrase where the adjective directly modifies the noun.

In Chinese, many short adjective + noun combinations do not need 的, especially when they are compact and common:

• 旧书 = old books
• 新衣服 = new clothes
• 大问题 = big problem
• 旧物 = old items

If you added 的, as in 旧的物品, it would sound more expanded and less compact. That is possible, but 旧物 is much more natural here.

Here 可以 means can in the sense of possibility or practical result.

It is not really about asking permission. It means:

Donating old items is able to / can help free up space.

So this is closer to:

• can
• is a way to
• can help

In Chinese, 可以 can express different ideas depending on context:

• 我可以进来吗？ = May I come in? → permission
• 这个办法可以解决问题。 = This method can solve the problem. → possibility/effectiveness

In your sentence, it is the second type.

腾出 means to free up, make available, or clear out.

It often suggests that space, time, or resources were occupied before, and now you create room by removing something.

Examples:

• 腾出空间 = free up space
• 腾出时间 = free up time
• 腾出一个座位 = make a seat available

In this sentence, 腾出空间 means that by donating old items, you create more room in your home or storage area.

Because 腾出 is the common verb pattern here.

The 出 adds the sense of bringing something out / creating an available result. It often marks the outcome of the action.

So:

• 腾出空间 = clear things away and as a result free up space

Without 出, 腾空间 is less standard in this meaning. Native speakers much more naturally say:

• 腾出空间
• 腾出时间

The 出 helps show the result clearly.

Yes, you can think of the sentence as having a general, unstated subject.

Chinese often leaves out subjects when the meaning is general or obvious. This sentence is basically making a general statement:

Donating old items can free up space.

It does not need to say:

• 你捐赠旧物，可以腾出空间。 = If you donate old items, you can free up space.
• 我们捐赠旧物，可以腾出空间。 = If we donate old items, we can free up space.

Without a specific subject, it sounds like a general truth or piece of advice.

Yes. Even though the literal structure is closer to Donating old items can free up space, in natural English it can also be understood as:

By donating old items, you can free up space.

Chinese often leaves this kind of interpretation open. Depending on context, it may sound like:

• a general statement
• a suggestion
• practical advice

So both English versions are reasonable.

Yes, 捐出旧物 can work, but the nuance is slightly different.

• 捐赠旧物 focuses on the act of donating in a standard or formal way.
• 捐出旧物 emphasizes giving the old items away/out.

Compare:

• 捐赠旧物可以腾出空间。
• 捐出旧物可以腾出空间。

Both are understandable. The first may sound a bit more like public-information language; the second may feel a bit more action-oriented.

Not in the same way. 旧物捐赠 sounds more like a noun phrase meaning old-item donation or the donation of used goods, not the action to donate old items.

Compare:

• 捐赠旧物可以腾出空间。 = Donating old items can free up space.
• 旧物捐赠活动很受欢迎。 = Old-item donation events are popular.

So if you want the sentence to talk about the action itself, 捐赠旧物 is better.

It sounds neutral to slightly formal, especially because of words like 捐赠 and 旧物.

It would fit well in:

• a poster
• a charity campaign
• a public service message
• an article
• practical lifestyle advice

A more casual version might be:

• 把旧东西捐出去，可以腾出空间。

That sounds more conversational, while 捐赠旧物可以腾出空间 is shorter and more polished.

Yes, if you want a more conversational style, you could say:

把旧物捐赠出去，可以腾出空间。

or more naturally in everyday speech:

把旧东西捐出去，可以腾出空间。

The original sentence is already correct, but the 把 version makes the action feel more concrete: you take the old items and donate them away. It is often used in spoken Chinese, while the original is more compact and slogan-like.

A few natural expansions are:

• 捐赠旧物可以腾出更多空间。
  Donating old items can free up even more space.

• 捐赠家里的旧物可以腾出空间。
  Donating old items from your home can free up space.

• 把不用的旧物捐出去，可以腾出空间。
  Donating unused old items can free up space.

• 捐赠旧物不仅可以腾出空间，还能帮助别人。
  Donating old items can not only free up space, but also help others.

These show how the same core structure can be used in everyday Chinese.