留学するは”study abroad”ですので、
I've studies abroad.
留学したことがあります。
I've studied abroad in England.
わたしはイギリスに留学したことがあります。
I studied abroad when-
わたしは、〜な時留学しました。
例)
I studied abroad when I was in high school.
わたしは高校時代に留学しました。
1. I've studied abroad.
"I've" is a shortened version of I have, which indicated something that you have done in the past.
2. I went abroad to study.
Whenever we use the word "went" in a sentence we are talking about an event that happened in the past.
Went is the past tense of go.
1. I've studied abroad.
"I've" は、I haveの短縮系で、何か過去に起こったことを表すために使います。
2. I went abroad to study.
"went"という動詞を使った場合、話している出来事は過去に起こったことという意味を与えます。
なぜならwentは、goの過去形だからです。
This is not my first time, I have already studied abroad for more than 2 years!
I have already " (done something) means...exactly that ;-)) it has been achieved!
in this case; studying abroad ..."has already been done..."
"This is not my first time, I have already studied abroad for more than 2 years!"
"I have already done something"とは何かをすでに達成した、経験がある、
という様な意味になります ;-))
この場合"studying abroad has already been done..."
(留学経験がある)と言う事になりますね。
【例】
"This is not my first time, I have already studied abroad for more than 2 years!"
(今回が初めてではありません。2年以上海外留学したことがあります)
>I have studied in a foreign country before.
>I have studied overseas before.
........................
*foreign country and overseas both indicate that it was abroad.
.......................
#Both phrases clearly indicate that you have had the opportunity to study abroad.
.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
>I have studied in a foreign country before.
>I have studied overseas before.
........................
*foreign country も overseasも、海外、外国を意味します。
.......................
#どちらのフレーズもはっきりと、留学する機会があった、と言うことを伝えます。
.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
There are a few ways you can say this.
You could refer to 'a foreign country,' which means any country other than your home country.
Or you may prefer to talk about your 'experience' of studying in another country.
Finally, you may choose to talk about the actual qualification that you gained in the foreign country:
"I did my degree in Newcastle, England."
"Oh, I did mine in Washington DC."
言い方はいくつかあります。a foreign countryといえば、自分の母国以外の国のことを言います。
自分の海外で留学した経験を話すこともできます。
最終的には、他国で学位を取得した経験を話すことができるでしょう。
例
"I did my degree in Newcastle, England."
イングランドニューカッスルで単位を取得したんだ。
"Oh, I did mine in Washington DC."
僕はDCでとったよ。
abroadはin a foreign countryやin an English-speaking countryや具体的な国名に変えてもよいです。
I have studied abroad.の直訳は「私は海外で勉強したことがある」です。
日本語は、難しい漢字を使って「経験者」のような名詞をよく多用する傾向がありますが、
英語は動詞を多用して(この場合のstudyのように)、「~する」「~した」のような形で」表現することが多いです。