dào le yīyuàn yǐhòu, wǒmen xiān qù guàhào, zài děng yīshēng.

They work together, but they are not exactly the same thing.

• 到医院 = arrive at the hospital
• 了 marks the action as completed
• 以后 = after

So 到了医院以后 means after arriving at the hospital.

A good way to see it is:

• 到医院以后 = after arriving at the hospital
• 吃完饭以后 = after finishing the meal
• 下课以后 = after class ends

So 以后 is the word that means after, while 了 helps show that the arrival has been completed.

Not exactly. 了 does not simply equal English past tense.

Here, 了 shows that the action arriving at the hospital is completed before the next actions happen. It helps create a sequence:

1. arrive at the hospital
2. register
3. wait for the doctor

So in this sentence, 了 is better understood as a completion marker, not just a generic past marker.

Because in Chinese, the verb 到 already includes the idea of arrive at / reach.

So:

• 到医院 = arrive at the hospital
• 到学校 = arrive at school
• 到北京 = arrive in Beijing

Unlike English, you do not need a separate word like to after 到.

Chinese very often puts time information before the main action.

So the structure is:

[When/after something happens], [main clause].

That is why this sentence begins with:

到了医院以后，...
= After arriving at the hospital, ...

This word order is very natural in Chinese. English can also do this, but Chinese uses it even more regularly.

先...再... is a very common pattern meaning:

• first... then...
• do A first, then do B

In this sentence:

• 先去挂号 = first go register
• 再等医生 = then wait for the doctor

So the structure is:

先 + action 1， 再 + action 2

Examples:

• 先吃饭，再去上课。 = Eat first, then go to class.
• 先洗手，再吃。 = Wash your hands first, then eat.

No. Here 再 means then / after that / next.

This is a very common confusion because 再 can also mean again in other contexts.

In this sentence:

• 先去挂号，再等医生 = first register, then wait for the doctor

It does not mean wait for the doctor again.

So you have to understand 再 from the context.

Yes, 挂号 is already a verb, and 去 is not strictly required in every situation.

Here, 去挂号 means something like:

• go register
• go and register

The 去 adds the idea of going to do that action, which sounds very natural in this hospital situation.

You could also hear:

• 我们先挂号，再等医生。

That is also grammatical. The version with 去 just feels a little more like we first go over to the registration desk and register.

In a hospital context, 挂号 means registering or checking in so you can see a doctor.

It is a hospital-specific word. It is not just any kind of registration in every context.

So when you go to a hospital or clinic in Chinese-speaking places, 挂号 often refers to the step where your name is entered and you get assigned for treatment or consultation.

Because 等 is a transitive verb, so it can directly take an object.

• 等医生 = wait for the doctor
• 等朋友 = wait for a friend
• 等车 = wait for the bus / a ride

So 等医生 is perfectly natural.

About the other forms:

• 等着医生 is usually not right here. 等着 is used differently and often describes a continuing state, but it does not fit well in this sentence.
• 等医生看我们 is more specific: wait for the doctor to see us. That is possible, but the original sentence is shorter and more natural in everyday speech.

Yes, you can.

Both of these are possible:

• 到医院以后
• 到了医院以后

The version with 了 emphasizes that the arrival is completed before the next action. Without 了, the sentence is still natural and understandable.

In many real situations, native speakers use both forms.

Yes.

You can say:

• 到了医院以后
• 到了医院后

Both mean after arriving at the hospital.

In general:

• 以后 is very common in speech and writing
• 后 can sound a little shorter or slightly more written/formal in some contexts

But both are correct here.

Yes, often it can.

If the subject is already clear from context, Chinese often leaves it out:

• 到了医院以后，先去挂号，再等医生。

This sounds natural if everyone already knows who is being talked about.

Including 我们 makes the sentence clearer and a bit more explicit, but omitting it is also very common in real Chinese.

Because 到了医院以后 is an introductory time phrase, and the comma helps separate it from the main clause.

So the sentence is divided like this:

• 到了医院以后， = after arriving at the hospital,
• 我们先去挂号，再等医生。 = we first register, then wait for the doctor.

In Chinese writing, commas are often used this way to make the structure easier to read.