■原句沒有錯，句中的but表明It has been raining for a day與even though it hadn't rained, we can't get there by tomorrow并列句；而even though則表明even though it hadn't rained是讓步狀語從句，而even though it hadn't rained, we can't get there by tomorrow是一個復合句。也就是說這是一個并列句中套用復合句的“并列復合句”。　　

你可以看看下面這篇文章，對你理解這類句子會有所幫助：http://www.hz123456.com/Article/200802/123.html　

■同意你的觀點，在rained 后可以加上yesterday這樣的時間狀語。　　

■注意：你原句中英文的標點前不能有空格，應改為：It has been raining for a day, but even though it hadn't rained, we can't get there by tomorrow. 由于我們的宗旨是要力爭把“英語語法網”做成全國最規范、最實用、最信得過的英語網站，所以對我們用戶朋友的要求有點“過分”，請諒解！