Family Mart is very busy today. I have not seen it like this before.
This is a formal/polite way of saying "I have never seen this Family Mart so crowded."
It explains that the shop is busy/crowded whilst telling the listener that you have not seen it like that before.
これは：
"I have never seen this Family Mart so crowded."
（このファミリーマートがこんなに混んでるのは見たことがない）
の丁寧（フォーマル）な言い方です。
お店が混んでいること、またそのお店がこんな風になるのは見たことがないと伝えています。
If you want to stress an adjective, just put 'so' in front of it. It is similar to 'very' but seems like more of an exclamation.
"Learning vocabulary is so boring!
形容詞を強調したい場合は、その前にsoを入れればオッケーです。veryと似てますが、より感情がこもります。
例：
Learning vocabulary is so boring!
ボキャブラリーを学ぶのは、めっちゃ退屈！
Today the Family Mart is unusually busy and crowded.
I've never experienced a crowd this big at this particular Family Mart.
This Family Mart is usually not so crowded, and today is the only time I've experienced this..
1.
"Unusually" is a good term to suggest that any other time that one has visited the store, it was not so crowded.
2.
If the statement applies to one Family Mart store and no others, it can be important to include that in the statement by saying, "this particular Family Mart."
3.
"Not so crowded" means that the store usually has fewer customers at any given time of day.
1.
「今までこんなに混んでいたことはなかった」は "Unusually"（異常に）で表すことができます。
2.
特定のファミリーマートについて言っているなら、それについて明示した方がいいです。"this particular Family Mart"（このファミリーマート）と言えます。
3.
"not so crowded"（こんなに混んでいない）は「普段はこの時間もっとお客さんが少ない」という意味です。
I've never seen this Family Mart so packed before.
This is the most packed I have ever seen Family Mart.
This is the most crowded I have ever seen Family Mart.
This is the most packed I have ever seen Family Mart. / This is the most crowded I have ever seen Family Mart. / I've never seen this Family Mart so packed before. - These sentences can be used to express that it's your first-time experience witnessing so many people inside of Family Mart. The word "packed" means "crowded".
For example, I have never seen this Family Mart so "crowded" before. I have never seen this Family Mart so "packed" before.
This is the most packed I have ever seen Family Mart.（こんなに混んでいるファミリーマートを見たのは初めてです）
This is the most crowded I have ever seen Family Mart.（こんなに混んでいるファミリーマートを見たのは初めてです）
I've never seen this Family Mart so packed before.（このファミリーマートがこんなに混んでいるのを見たのは初めてです）
これらの文は「こんなに混んでいるファミリーマートを見たのは初めて」と言いたいときに使うことができます。
"packed" は "crowded"（混雑した）という意味です。
例えば：
I have never seen this Family Mart so "crowded" before.
I have never seen this Family Mart so "packed" before.
（このファミリーマートがこんなに混んでいるのを見たのは初めてです）
This family mart is the most packed I have ever seen it.
I have never seen this family mart so packed before.
This family mart is never normally this crowded.
If you are trying to say that this family mart is the most crowded you have ever seen it, you may say something like "I have never seen this family mart so packed before." or "this family mart is never normally this crowded." The word "packed" is just another word that means crowded or filled with many people.
「このファミリーマートがこんなに混んでいるのを見たのは初めて」は次のように言えます。
"I have never seen this family mart so packed before."（このファミリーマートがこんなに混んでいるのを見たのは初めて）
"This family mart is never normally this crowded."（このファミリーマートは普段はこんなに混むことはない）
"packed" は「混雑した／人でいっぱいの」という意味です。
I'm shocked to see it this busy, it is the first time I see so many people here.
To express that a place is busier than usual you can say that the place is 'full' or 'congested,' these mean that there are many people there.
Usually, places fill up after pay dates have passed near the end of the month.
Congested: so full you can't move around freely
"Did you see how full it was at the Family Mart this weekend?"
どこかが普段よりも混み合っているなら、それは "full" や "congested" で表すことができます。これらは、人がたくさんいることを表します。
月末の給料日を過ぎると、お店などは混雑しやすいです。
Congested: 身動きが取れないほど混雑した
"Did you see how full it was at the Family Mart this weekend?"
（先週末ファミリーマートがすごく混んでいたよね）
It isn't normally this crowded, they are very busy today.
Point out that it is unusual for there to be so many people in this store and that normally it is much quieter with only a few customers.
'Crowded' suggests it is so full there is little room to move.
"This is the most packed I have ever seen Family Mart"
If you were at a convenience store called Family Mart and you wanted to express that it is really crowded today and you have never seen it so crowded, you could say any of the following: "I have never seen this Family Mart so crowded", "I have never seen Family Mart so busy before" or "This is the most packed I have ever seen Family Mart".
ファミリーマートというコンビニにいるのですね。すごく混んでいると。「こんなに混んでいるのは見たことがない」、これは次のように表せます。
"I have never seen this Family Mart so crowded"（このファミリーマートがこんなに混んでいるのは見たことがない）
"I have never seen Family Mart so busy before"（ファミリーマートがこんなに混んでいるのは見たことがない）
"This is the most packed I have ever seen Family Mart"（ファミリーマートがこんなに混んでいるのを見たのは初めて）
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