I need English to gain an insight into other cultures
Well, it depends which aspects of 'other worlds' you are interested in. Very generally, you can speak in terms of broadening your horizons or gaining an insight into things.
I feel like if I become fluent in English I can see the world on a new perceptive.
*I feel like if I become fluent in English I can see the world on a new perceptive.
Fluent means to be able to speak English very well.
Perceptive refers to the way you see things.
In this case it means that if you speak English you are able to understand things you could not understand before because you could not speak English.
*I feel like if I become fluent in English I can see the world on a new perceptive.
Fluentはペラペラや流暢という意味です。
Perceptive は様々な視点のことです。
この場合は英語を話せるようになって視野が広がったという意味です。
Learning English will open me up to a world of possibilities.
I want to learn English as a gateway to new worlds.
a gateway to new worlds - something that is a gateway to new worlds is a tool that allows you to travel and see more of the world.
A.Why are you learning English?
B. I love foreign languages. Besides, English is spoken almost everywhere. It is a gateway to new worlds.
a gateway to new worlds -新しい世界を見せてくれるツール。
（英文）
A.Why are you learning English?
B. I love foreign languages. Besides, English is spoken almost everywhere. It is a gateway to new worlds.
（訳）
A:なぜ英語を勉強しているのですか？
B:いろんな言語を勉強するのが好きです。新しい世界を見せてくれるのです。
By speaking English one is able to explore and experience the world differently.
By speaking English I am able to experience the world with a new perspective.
To express that one is able to see things differently when speaking English one might say the following;
By speaking English one is able to explore and experience the world differently.
By speaking English I am able to experience the world with a new perspective.
keywords:
experience the world differently- Seeing things in a new way.
perspective-Your attitude to how you see things and point of view.
英語を話すと物事について違う見方ができると表すなら：
By speaking English one is able to explore and experience the world differently.
（英語を話すことで、世の中について違う見方ができる）
By speaking English I am able to experience the world with a new perspective.
（英語を話すことで、世の中について違う見方ができる）
experience the world differently- 物事について違う見方をする
perspective- 物事の見方、考え方
Becoming a fluent English speaker will enable me to travel the world, see new places and make many new friends.
Since English is spoken all over the world, one will have a big advantage of seeing new places and making new friends if he/she speaks the language. One will be able to communicate with people wherever he/she travels to in the world. One will be able to tell stories and joke with complete strangers and thereby make new friends. It is satisfying to see new places and learn about those places and cultures of people living there. It is advantageous to be a fluent English speaker.
So, you may say:
Becoming a fluent English speaker will enable me to travel the world, see new places and make many new friends.
英語が話せれば、いろいろな人と出会い、いろいろな場所に行くことができます。
世界中どこに行ってもコミュニケーションできます、知らない人と話をして、冗談を言って友達が作れます。
行ったことのない場所に行って、そこの文化を学ぶのは楽しいです。英語を話せると得です。
例えば：
Becoming a fluent English speaker will enable me to travel the world, see new places and make many new friends.
（英語が話せると、世界を旅して、たくさん友達が作れる）
アメリカ合衆国 
イギリス 
日本 
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