YOU SAID:
He wasn't able to eat rice right away.
INTO JAPANESE
彼はすぐにご飯を食べることができませんでした。
BACK INTO ENGLISH
He couldn't eat dinner soon.
INTO JAPANESE
彼は、すぐに夕食を食べることができませんでした。
BACK INTO ENGLISH
He couldn't eat dinner soon.
That didn't even make that much sense in English.