Learn Hardcore Chinese: wèile zhè cì lǚyóu, wǒmen yǐjīng mǎi hǎo huílái de jīpiào. - For this trip we’ve already bought the return plane tickets.

In this sentence, 为了 should be understood as a fixed unit meaning “for / for the sake of / in order to”.
Here, 了 is not the past‑tense/aspect particle; it is part of the preposition 为了 that introduces a purpose.

为了 + noun / verb phrase = “for / in order to …”
- 为了这次旅游 = for this trip / for the sake of this trip

So 为了 here does not tell you anything about tense; it just introduces the reason/purpose.

Could I just say 为这次旅游 instead of 为了这次旅游? What’s the difference?

Yes, you can say 为这次旅游; it is grammatically correct.

Differences:

为了 is more common in everyday speech when you’re clearly expressing purpose (“in order to”).
为 alone can sound a bit more formal or written, and is often used in set phrases (为人民服务, 为……而努力, etc.).
In many contexts they are interchangeable, but 为了 feels slightly more conversational and explicit about purpose.

Here, 为了这次旅游 is the most natural, neutral choice in spoken Mandarin.

Why do we need 次 (cì) in 这次旅游? Why not just 这旅游?

旅游 is originally a verb (“to travel, to go sightseeing”) that can also be used as a noun (“travel, tourism”).
To say “this trip” / “this time we travel”, Chinese typically uses a measure word for occurrences: 次, meaning “time, occasion”.

这次旅游 = this trip / this time’s traveling
这旅游 ❌ sounds wrong/unnatural; you normally can’t stick 这 directly before 旅游 without a measure word.

So 这 + 次 + 旅游 is the natural structure: demonstrative + measure word + activity.

What’s the difference between 旅游 (lǚyóu) and 旅行 (lǚxíng)? Could I say 这次旅行 instead?

You can absolutely say 为了这次旅行，我们已经买好回来的机票。 It’s correct and natural.

Nuance:

旅游 often suggests sightseeing, vacation travel, leisure.
旅行 is a bit broader: journey, travel, not necessarily just for fun (could be business travel, long journeys, etc.).

In many everyday contexts, the two overlap and are interchangeable. The original sentence leans slightly toward “this vacation trip” by using 旅游.

Why is 已经 (yǐjīng) used here? Do we also need a 了 at the end of the sentence?

已经 means “already” and is used together with a completed or achieved action. Here it emphasizes that the tickets are already purchased and ready.

In this sentence, completion is expressed by:

已经 (“already”)
plus the result complement 好 in 买好

Because 买好 already shows the action is complete and successful, you do not need an extra 了 at the end.

You could say:

我们已经买好了回来的机票。
This adds the aspect particle 了 after the verb phrase; it’s still natural and slightly emphasizes the completed result, but it is not required.

What does 买好 (mǎihǎo) mean? How is it different from just 买了?

买好 is 买 (to buy) + the result complement 好, which means “successfully / properly / ready”.

So:

买了 = bought (the action happened; neutral about the result)
买好 = have bought and everything is ready / taken care of

In the context of tickets:

我们已经买了回来的机票。= We have bought the return tickets (fact).
我们已经买好回来的机票。= We have bought the return tickets and they’re sorted / all set (focus on the satisfactory, completed result).

The original sentence wants to stress that the preparation for the trip is properly done, so 买好 is very natural.

What exactly does the 好 in 买好 mean? Is it “good”?

Here, 好 is not “good” in the usual descriptive sense; it is a resultative complement meaning “finished, properly, ready”.

Common patterns with V + 好:

准备好 (zhǔnbèihǎo) – prepare something and have it ready
安排好 (ānpáihǎo) – arrange something well, arrangements are set
想好 (xiǎnghǎo) – think something through and have decided
订好 (dìnghǎo) – book something successfully

So 买好机票 means “have the tickets bought and ready,” not “buy good tickets.”

What does 回来的机票 literally mean? Why is 的 there?

回来的机票 is a modifier + noun structure:

回来 = “come back, return (here)”
的 = turns the preceding phrase into an adjectival/attributive modifier
机票 = plane ticket

So literally: “the ticket (for) coming back”, i.e. the return ticket.

In Chinese, when a verb phrase modifies a noun, you almost always need 的:

回来的机票 = the ticket (for) coming back
去北京的火车票 = the train ticket (for) going to Beijing
Here, 回来的 functions like an adjective in front of 机票.

Why is it 回来 and not 回去 in 回来的机票?

The choice between 来 (come) and 去 (go) depends on the direction relative to the speaker or a reference point.

回来: return to here / to the speaker’s home base or starting point.
回去: go back away from here / to some other place.

In context, they are talking about a trip away from home and the ticket to come back home (to “here”). So 回来的机票 = the ticket for returning here, i.e. the return leg of the journey. That’s why 回来 is used, not 回去.

Is 回来的机票 the normal way to say “return ticket”? Are there more formal alternatives?

Yes, 回来的机票 is a very natural, everyday way to say “the return ticket”.

More formal or concise alternatives include:

回程机票 (huíchéng jīpiào) – literally “return‑journey ticket,” very common in booking/travel contexts.
返程机票 (fǎnchéng jīpiào) – similar to 回程, slightly more formal.

So you could also say:

我们已经买好回程机票。
我们已经买好返程机票。
All of these are correct; the original simply uses a more descriptive phrasing.

Can I change the word order to 我们已经把回来的机票买好了? Is that the same?

Yes, 我们已经把回来的机票买好了 is grammatical and natural. It uses the “把” construction:

把 + object + verb + result/particle

Comparing:

我们已经买好回来的机票。
我们已经把回来的机票买好了。

Meaning is essentially the same: you’ve already bought and settled the return tickets.
The 把‑sentence puts extra focus on “what happened to the object” (the tickets have been taken care of), but the difference in nuance is small here.

Could 为了这次旅游 go at the end of the sentence instead of at the beginning?

You could say something like:

我们已经买好回来的机票，为了这次旅游。

Grammatically, this can work, but:

Putting 为了这次旅游 at the beginning is the most natural way to set up the purpose right away.
If you put it at the end, it can sound a bit like an afterthought or extra explanation.

So in standard, neutral style, 为了这次旅游 is best placed at the beginning, just as in the original sentence.