korien_feb10“I had almost solved the problem when the doorbell rang and I lost my train of thought.”

When thinking, one thought leads to another. The thoughts are connected like cars on a train.

Saying you lost your train of thought is perfectly normal. If you say your train of thought was derailed, it becomes a play on words.



train of thought「考えの電車」を逃してしまったというフレーズは普通に使います。train of thought「考えの電車」が脱線したなどと言ったら、駄じゃれになりますよ。