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to apply (of a rule); to be applicable (of standards, lessons, ideas, etc.); to hold true (e.g. of a description); to fit; to be suitable (e.g. of a word); to meet (requirements); to fulfill (conditions); to come under (a heading)
この規則は全ての場合に当て嵌まるわけではない。
This rule does not apply in all cases.
彼の説明は事実に当て嵌まっている。
His explanation fits the facts.
その条件に当て嵌まる人は意外と少ない。
Surprisingly few people meet those criteria.