I have a poor memory.
「私の記憶力は乏しい」
I have a short memory.
「私の記憶力は短い」
どちらを使っても大丈夫ですがわたしは個人的にI have a short memoryのほうを使うことが多いです。
I'm bad at memorizing.は私は[暗記](https://eikaiwa.dmm.com/uknow/questions/7366/)（記憶）するのが[苦手](https://eikaiwa.dmm.com/uknow/questions/71084/)だ、という意味です。
1. Memory retention = the ability to remember things.
"I can't believe how bad John's memory retention is!"
2. As soon as = the moment that.
3. To have a memory/mind like a sieve is an idiom which means to be very bad at remembering things "I've never known anyone so forgetful - she's got a memory like a sieve."
1. Memory retention = 覚えることのできる能力
"I can't believe how bad John's memory retention is!"：ジョンったら本当に忘れっぽいのよ。
2. As soon as = その瞬間に、
3. To have a memory/mind like a sieveは、イディオムで何かを覚えるのがすごく苦手という意味です。
"I've never known anyone so forgetful - she's got a memory like a sieve."
こんなに忘れっぽい人初めて見た！彼女って本当に覚えるのが苦手なのね
The words won't stick in my mind - this means your brain can;t remember them - they disappear quickly.
I have the memory of a goldfish - this means you forget things very quickly and easily and don;t remember many things.
I have a memory like a sieve - a sieve is a bowl with holes in that we use to wash vegetables and the water to run out of the holes. When we say we have a memory like a sieve we are saying that things run out of mind (like the water) and don't stay in our mind or brain.
Hope this helps
Jane :)
The words won't stick in my mind.
- これはあなたの脳が単語を覚えることができないという意味です。
単語がすぐにどこかへ消えてしまいます。
I have the memory of a goldfish.
- これはあなたがとても忘れっぽくてたくさんのことを覚えられないことを意味します。
I have a memory like a sieve.
- sieve は野菜を洗う時に使う穴の開いたボウルで、水をよく通します。
ザルのような記憶力ということで、（水のように）脳から記憶が抜け落ちてしまい、頭や脳の中に残らないことを意味します。
参考になれば幸いです。
Even if I remember vocabularies once, I forget immediately.
I always forget the singer's name. この歌手の名前いつも忘れてしまいます。
I am so easy to forget.. 私は物忘れが激しいです。
Even if I remember vocabularies once, I forget immediately. 一度単語を覚えたとしても、すぐに忘れてしまいます。Even if = ~ だとしても immediately= すぐに
参考になれば幸いです。
ご質問ありがとうございます。
・「I have poor memory and I keep forgetting it.」
（意味)記憶力が悪くていつも忘れてしまいます。
<例文> What was that singer's name? I have poor memory and I keep forgetting it.
<訳>その歌手の名前何だった？記憶力が悪くていつも忘れてしまいます。
参考になれば幸いです。
We can talk about, "short-term memory," in regards to the type of memory that is learned recently. We can talk about how, "I forget things I recently learned," as well to have the same meaning. Lastly we can talk about, "memorizing," as this refers to making sure that we don't forget the things that we recently learned.
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