there are fewer opportunities for us to write by hand so there are some kanji I can't remember how to write straight away.
We don't write by hand so much these days so I sometimes forget how to write certain kanji
I can remember (how to write) most kanji but recently we use smartphones and computers more so there are some kanji that I forget how to write.
「手書きの機会が減ったのですぐに思い出せない漢字もあるかも」
＝ there are fewer opportunities for us to write by hand so there are some kanji I can't remember how to write straight away.
We don't write by hand so much these days so I sometimes forget how to write certain kanji
「だいたいは覚えているけど最近はパソコンやスマホで打つことが多いので
忘れている漢字もあるかもしれない」
I can remember (how to write) most kanji but recently we use smartphones and computers more so there are some kanji that I forget how to write.
There are fewer opportunities for people to actually write Japanese these days, so there are probably some Kanji I have forgotten how to write.
この場合、次のような言い方ができますよ。
ーThere are fewer opportunities for people to actually write Japanese these days, so there are probably some Kanji I have forgotten how to write.
「最近実際に日本語を書く機会が減ってきているので、書き方を忘れた漢字がいくつかあると思う」
to forget how to write で「どうやって書くか忘れる」
ご参考まで！
"I can remember most of the kanji, but with frequent use of computers and smartphones these days, there may be some kanji that I forget how to write by hand."
"I can remember most of the kanji, but with frequent use of computers and smartphones these days, there may be some kanji that I forget how to write by hand."
ここで、「I can remember most of the kanji」で「ほとんどの漢字は覚えています」と伝えている部分と、「but with frequent use of computers and smartphones these days, there may be some kanji that I forget how to write by hand」で「しかし、最近はコンピュータやスマートフォンをよく使うので、手書きすると時々どのように書くか忘れてしまう漢字もあります」と渡邉さんの状況を説明しています。
参考：
- remember: 記憶する
- forget: 忘れる
- kanji: 漢字
- write by hand: 手書きする
- computers and smartphones: コンピューターとスマートフォン
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アメリカ合衆国 
