I unintentionally caught a glimpse of the other student's paper
If you do something that you did not mean to do then you do that 'unintentionally.'
"As Mike was about to score, he unintentionally dropped the ball and fell over."
To catch a glimpse - this means to see something briefly - possiobly ony for a fraction of a second.
"The paparazzi caught a glimpse of the star's underwear as she got our of the car."
何かをやるつもりはなかったけど、やってしまったことを
'unintentionally'（意図的ではなく/気づかずに）と言います。
【例】
"As Mike was about to score, he unintentionally dropped the ball and fell over."
（マイクがゴールを決めようとしている時、不意にボールを落として転んでしまった）
To catch a glimpse （ちらりと見る/一目見る）
-これはほんの一瞬何かを見るという意味になります。
【例】
"The paparazzi caught a glimpse of the star's underwear as she got our of the car."
（スターが車を降りる時にパパラッチは彼女の下着をちらっと見た）
By stating that you accidentally saw the paper, then you are implying that you had no intention of looking, it just caught your eye. It is natural for us to look at something we shouldn't if we are given a clear view of it. Like if a student moved out of the way of the paper and you happened to be looking at the same time. That is when someone catches your eye,
I accidentally caught a glimpse of her exam/test paper.
*I accidentally caught a glimpse of her exam/test paper. - Accident means something done unintentionally or not on purpose. If caught staring at someone's paper this can be regarded as cheating.
Example Sentences:
My teacher almost disqualified my science test paper, I accidentally looked at the paper of the person seated in front of me.
She accidentally caught a glimpse of his security details as he was flipping his phone in the car.
"I accidentally caught a glimpse of her exam/test paper."
(私は偶然彼女のテスト答案用紙をチラっとみえてしまった。)
"Accidentally "とは、無意識に、わざとではない、という意味です。
誰かの回答をじっと見つめているのは、カンニングになります。
例文
"My teacher almost disqualified my science test paper. I accidentally looked at the paper of the person seated in front of me."
(私の先生は理科のテストを剥奪仕掛けました。というのも私は、偶然前の席に座っている人の回答用紙を見てしまいました。)
"She accidentally caught a glimpse of his security details as he was flipping his phone in the car."
(彼が車の中で携帯を使っていたので、彼女は偶然ロックの情報を見てしまいました。)
I have sometimes seen someone else paper by accident never on purpose.
"I saw it by accident I have never tried to cheat." This explains that it was just by chance that you saw the page and that you never try to see it on purpose.
"I have sometimes seen someone else paper by accident never on purpose." This is another way of explaining that you didn't try and see the answer on the other person's page.
例文
"I saw it by accident I have never tried to cheat."
偶然見たことはあるけど、カンニングしようとしたことは一度もない
答案を見たことはほんの偶然で、故意に見ようとしたことは一度もないということを説明しています。
例文
"I have sometimes seen someone else paper by accident never on purpose."
偶然他の人の答案を見たことはあるけど、故意では決してない
他人の答案の答えを見ようとしたことはないと説明する別の表現です。
I've seen someone else's paper before, but not on purpose.
On accident, I have seen it, but it was not on purpose.
To say that during a test that you say a person's test paper before, but it wasn't on purpose, you can state it like this: "I've seen someone else's paper before, but not on purpose."
「他の人の答案は、偶然見たことはあるけど故意にはない」は次のように言えます。
"I've seen someone else's paper before, but not on purpose."（他の人の答案を見たことはあるけど故意にはない）
I accidentally saw a glimpse of the other student's paper
I accidentally saw their paper
If you don't mean to do something but it happens then this is called an 'accident' so you can say you 'accidentally'
to have a quick look this is called a 'glimpse'
paper refers to the exam paper
イギリス 
アメリカ合衆国 
南アフリカ 
