Fully understanding the difference between もう and －たことがある


I my understanding, the **difference between もう and －たことがある** is as follow:

  * **もう** is for **" already"** like in:

>   * I've (already) eaten my sandwich
>   * I've (already) been shopping yesterday
>

  * **ーたことがある** is for **experiences** as in

>   * I've been to / I visited Spain
>   * I used to play / played football
>

The form you choose is very important it seems, as you can say a very
different thing with the other one _(`I have eaten a sandwich once` is not the
same as `I've eaten my sandwich`)_

**But** in my book I found these sentences, for which I would have used the
ーたことがある form:

>   * もう びじゅつかん に 行{い}きましたか。
>   * もう かんこう バス に のりましたか。
>   * もう 日本{にほん} の りょうり を 食{た}べましたか。
>   * もう さくら を 見{み}に 行{い}きましたか。
>

* * *

Therefore **my question is** :

  * Is it just possible for some cases to use both form that would **mean the same thing**?

  * Did I miss something? Is there something I did not understand (properly)?

* * *

_**Bonus:**_

_Would the sentence below be better translated by either one of the
propositions? If not, what would be the difference?_

> I've read this book:
>
>   * この本{ほん} を もう 読{よ}みました。
>
>   * この本{ほん} を 読{よ}んだことがあります。
>
>

_And is もう properly placed either at the beginning or in the middle of a
sentence?_




# Standalone もう～ vs Standalone ～たことがある

I think もう～ and ～たことがある are different in the same way that **a/an** and
**the** are used differently in English, _at least for most_ of the examples
that you gave. So **I don't think that there are cases when both forms would
mean the same thing** , _if we are talking about them being not used together
in the same sentence._

_For cases where もう～ is used together with ～たことがある see near the bottom of this
answer._

Let us look at these examples.

> 1a. リンゴをもう食べた

I ate **the** apple

The apple that the speaker ate is very specific. The speaker wants the
listener to know that s/he already ate the apple that the latter knows about.

> 1b. リンゴを食べたことがある

I have eaten **an** apple

The speaker has eaten an apple before. The speaker wants the listener to know
that if s/he is going to eat one again, it won't be the first time.

Going back to one of your examples.

> 2a. もう びじゅつかん に 行きましたか。

Have you been to **the** art museum?

The speaker is asking if the listener has visited a specific art museum, and
not just any other anywhere else.

> 2b. びじゅつかん に 行ったことがありますか。

Have you been to **an** art museum?

The speaker is asking if the listener has ever been to one.

The same will work for your other examples too. In the case of:

> 3a. もう 日本 の りょうり を 食べましたか。

it could be that they were in a hotel that serves different foods from various
countries and the speaker is asking if the listener has tried the Japanese
food that the hotel serves. If you change that to:

> 3b. 日本 の りょうり を 食べたことがありますか。

the speaker is just asking if the listener has eaten Japanese food before.

* * *

One of the examples that you gave in English is **I've been to / I visited
Spain**. If I were to use もう～ and ～たことがある, they would look like:

> 4a. もうスペインに行きました

This could mean that the speaker was planning to go to Spain, and has already
gone there, and the listener knew about this plan.

> 4b. スペインに行ったことがある

This means that the speaker has already visited Spain in the past.

* * *

# Issue about proximity in time

もう connotes that something specific – it could be a plan or some other thing
that the listener _knows about_ – has been done. ことがある on the other hand just
means something has been done before. I don't think either of the two is
affected by time, so it does not matter if what was done happened 50 yrs ago
or yesterday. For example:

> Aさん：昔{むかし}、スペインに行きたいと言っていたのを覚えている

A: Do you remember the time when you said that you wanted to go to Spain?

Say the answer is:

> Bさん：１０年前{ねんまえ}にもう行きましたよ

In this case, B told A (say 20 yrs ago) about his wish, and when asked by A
now (maybe they haven't seen each other in a while), B said that he already
went there 10 years ago. So we can see that もう _does not have_ to be something
very recent.

For ～たことがある, I think it is clear that time proximity also does not matter as
one could have experienced something decades ago or just now.

* * *

# Combined use of もう～ and ～たことがある

Note that もう could be added to a sentence with ～ことがある as in the following
example.

> あの人とは知り合ったばっかりだが、 **もう** 喧嘩したことがある

I have just met that person, but we already had a quarrel

* * *

# Bonus

For your bonus, you gave two options on how to translate **I've read this
book** as follows. I will try to explain the difference using imaginary
situations.

> この本 を もう 読みました。

In this translation, it could be that the listener knew that the speaker was
going to read the book and asked him/her if he already read it. It could be
also that the listener told/ordered the speaker to read it, so the speaker is
now telling the listener that he's done reading.

> この本 を 読んだことがあります。

In this translation, the speaker is just saying that he read the book before.
Maybe he was replying to a question like この本は知っている？ (Do you know this book?)

Lastly, the answer to your question below is "Yes, it is."

> is もう properly placed either at the beginning or in the middle of a
> sentence?




# Standalone もう～ vs Standalone ～たことがある

I think もう～ and ～たことがある are different in the same way that **a/an** and
**the** are used differently in English, _at least for most_ of the examples
that you gave. So **I don't think that there are cases when both forms would
mean the same thing** , _if we are talking about them being not used together
in the same sentence._

_For cases where もう～ is used together with ～たことがある see near the bottom of this
answer._

Let us look at these examples.

> 1a. リンゴをもう食べた

I ate **the** apple

The apple that the speaker ate is very specific. The speaker wants the
listener to know that s/he already ate the apple that the latter knows about.

> 1b. リンゴを食べたことがある

I have eaten **an** apple

The speaker has eaten an apple before. The speaker wants the listener to know
that if s/he is going to eat one again, it won't be the first time.

Going back to one of your examples.

> 2a. もう びじゅつかん に 行きましたか。

Have you been to **the** art museum?

The speaker is asking if the listener has visited a specific art museum, and
not just any other anywhere else.

> 2b. びじゅつかん に 行ったことがありますか。

Have you been to **an** art museum?

The speaker is asking if the listener has ever been to one.

The same will work for your other examples too. In the case of:

> 3a. もう 日本 の りょうり を 食べましたか。

it could be that they were in a hotel that serves different foods from various
countries and the speaker is asking if the listener has tried the Japanese
food that the hotel serves. If you change that to:

> 3b. 日本 の りょうり を 食べたことがありますか。

the speaker is just asking if the listener has eaten Japanese food before.

* * *

One of the examples that you gave in English is **I've been to / I visited
Spain**. If I were to use もう～ and ～たことがある, they would look like:

> 4a. もうスペインに行きました

This could mean that the speaker was planning to go to Spain, and has already
gone there, and the listener knew about this plan.

> 4b. スペインに行ったことがある

This means that the speaker has already visited Spain in the past.

* * *

# Issue about proximity in time

もう connotes that something specific – it could be a plan or some other thing
that the listener _knows about_ – has been done. ことがある on the other hand just
means something has been done before. I don't think either of the two is
affected by time, so it does not matter if what was done happened 50 yrs ago
or yesterday. For example:

> Aさん：昔{むかし}、スペインに行きたいと言っていたのを覚えている

A: Do you remember the time when you said that you wanted to go to Spain?

Say the answer is:

> Bさん：１０年前{ねんまえ}にもう行きましたよ

In this case, B told A (say 20 yrs ago) about his wish, and when asked by A
now (maybe they haven't seen each other in a while), B said that he already
went there 10 years ago. So we can see that もう _does not have_ to be something
very recent.

For ～たことがある, I think it is clear that time proximity also does not matter as
one could have experienced something decades ago or just now.

* * *

# Combined use of もう～ and ～たことがある

Note that もう could be added to a sentence with ～ことがある as in the following
example.

> あの人とは知り合ったばっかりだが、 **もう** 喧嘩したことがある

I have just met that person, but we already had a quarrel

* * *

# Bonus

For your bonus, you gave two options on how to translate **I've read this
book** as follows. I will try to explain the difference using imaginary
situations.

> この本 を もう 読みました。

In this translation, it could be that the listener knew that the speaker was
going to read the book and asked him/her if he already read it. It could be
also that the listener told/ordered the speaker to read it, so the speaker is
now telling the listener that he's done reading.

> この本 を 読んだことがあります。

In this translation, the speaker is just saying that he read the book before.
Maybe he was replying to a question like この本は知っている？ (Do you know this book?)

Lastly, the answer to your question below is "Yes, it is."

> is もう properly placed either at the beginning or in the middle of a
> sentence?

