「昼食と夕食の間隔が長い」の直訳は The interval between lunch and dinner is longになります。
昼食 - lunch
夕食- dinner
間隔 - space, interval
長い - long
もっと自然な言い方だと
I eat breakfast at 7, I have lunch at 12 and then I have dinner at 9. There's a big gap between lunch and dinner.
...After I eat lunch I have to wait a really long time before (I have) dinner.
もしくは...I have a 9 hour gap between lunch and dinner になります。
There are a lot of hours between my lunch time and supper time.
この場合、次のような言い方ができますよ。
ーIt's a long time between lunch and supper.
「昼食と夕食の間が長い時間だ」＝「昼食と夕食の間隔が長い」
ーThere are a lot of hours between my lunch time and supper time.
「お昼の時間と夕食の時間の間に長い時間がある」＝「昼食と夕食の間隔が長い」
ご参考まで！
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