This has year has been one of the most important periods of my life.
"This year has been one of the most important periods of my life."
-just like you have 'periods of time,' you can also have 'periods of your life.'
Elementary school was a period of my life when I didn't have any independence because I was still just a child and beholden to the adults in my life.
High school was a period of my life when I was rebellious because I had a lot of teenage angst, and I needed to branch out from my parents.
"This has year has been one of the most important periods of my life."
（今年は私にとってとても重要な一年でした）
-この'periods of time（期間）、'と同じように 'periods of your life'を使う事も出来ます。
【例文】
Elementary school was a period of my life when I didn't have any independence because I was still just a child and beholden to the adults in my life.
（小学生の時、私はただの子供で大人に世話をしてもらっていたので、全く自立していませんでした）
High school was a period of my life when I was rebellious because I had a lot of teenage angst, and I needed to branch out from my parents.
（高校時代は沢山の十代の不安があり親から離れたくて、私は反抗期でした）
So much has happened; this past year has been crucial for me in so many ways!
Crucial: Decisive or critical, especially in the success or failure of something.
When something is described as crucial it is " of great importance!"
"So much has happened; this past year has been crucial for me ... in so many ways!"
Crucial: 特に何かを成功又は失敗する時に決定的な、とても重要だということです
crucial と表現することは、とても重要だということです。
例文
"So much has happened; this past year has been crucial for me ... in so many ways!"
本当に多くのことがありました。この1年はとても多くの点で私にとって重要な年でした。
When something is crucial it is very important or has a great importance to someone
So by saying "this past year has been a crucial part of my life" it means that the past year has been of great importance to you.
「crucial」は「とても重要な」という意味です。
"This past year has been a crucial part of my life"
「この一年は私の人生にとってとても重要な時間になっています」
- この一年は自分にとってとても大切だったと言っています。
"This past year was a very crucial time in my life".
Synonyms for the word important include: crucial, vital, and major.
For example: This past year has was a very major year for me.
But most commonly, we use the term "life-changing" to describe something that has had a significant impact on a person's life.
For example: Last year was life changing for me.
Last year was a very significant time in my life.
"This past year was a very crucial time in my life".
（この一年は私の人生でとても重要な期間でした）
"important"の同義語には以下のようなものがあります：
crucial, vital, major
例文：
This past year was a very major year for me.
（この一年は私にとってとても重要な期間でした）
ただ、人生に重大な影響を及ぼしたことについて言う場合は、"life-changing"という表現が一般的です。
例文：
Last year was life changing for me.
（昨年は、私にとって人生の転機でした）
Last year was a very significant time in my life.
（昨年は私の人生でとても重要な期間でした）
A landmark - a significant or historic event, juncture, achievement, etc.:
"The court decision stands as a landmark in constitutional law."
Critical - A critical time, factor, or situation is extremely important.
"The incident happened at a critical point in the campaign."
"Environmentalists say a critical factor in the city's pollution is its population."
"He says setting priorities is of critical importance."
"How you finance a business is critical to the success of your venture."
A landmark - 重要な、歴史上の出来事、岐路、成果
例文
"The court decision stands as a landmark in constitutional law."
その裁判所の判決は 、憲法における画期的な出来事だ。
Critical - A critical time, factor, or situationはとても重要だということです。
例文
"The incident happened at a critical point in the campaign."
その事件は、キャンペーンにおいて重要な時期に起こった。
"Environmentalists say a critical factor in the city's pollution is its population."
都市の汚染の重要な要因は、人口だと環境保護主義者は言っている。
"He says setting priorities is of critical importance."
優先順位を決めることはとても重要だと彼は言っている。
"How you finance a business is critical to the success of your venture."
事業の資金をどのように調達するかが、事業の成功にはとても重要だ。
The two sentences you see provided above are terrific ways to express to your listener that this past year was very important. In the first sentence you will notice the word incredibly and in the second sentence you will notice the word extremely. Both of these words mean very. These words are common in our everyday conversation and appropriate for a formal setting as well. They would make great additions to your vocabulary.
This year proved to be of monumental importance to me.
This past year has proved to hold paramount significance in my life.
English is a beautiful and expressive language. As English speakers, we aim to be eloquent and clear. When trying to stress the importance of something one may use various adjectives. You may say something is; momentous, of monumental importance, of paramount importance, of great consequence or of supreme.Theses adjectives stress and emphasize the something is or has been critical and of great value.
英語は美しく、表現力が豊かな言葉です。英語を話す人として、説得力があり、明確に話すように努めています。
物事の重要性を強調しようとする時は、様々な形容詞を使うことが出来ます。momentous, of monumental importance, of paramount importance, of great consequence,of supremeのような語を使うことが出来ます。これらの形容詞は、あることが今もこれまでもずっと重要で、とても価値があるものだったということを強調しています。
When you want to explain to a person that the past year was very important to you, then you can say:
-This past year was a very important for me
-This past year was a crucial period in my life
Remember, it may be important in some cases to elaborate. You may say something like,
-This past year was very important to me because I was working towards finishing my first undergraduate degree.
この一年間がとても大切だったと伝える言い方です：
【例文】
-This past year was a very important for me
（この一年間は私にとってとても大切な期間でした）
-This past year was a crucial period in my life
（この1年間は私の人生にとってとても大切な期間でした）
なぜ大切な年なのかより詳しく伝えた方がいい場合もあるかもしれません。
次のように言うことが出来ます：
-This past year was very important to me because I was working towards finishing my first undergraduate degree.
（この一年は、学部課程を初めて終わらせる年だったので、私のとってとても大切でした）
アメリカ合衆国 
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