在炎热的夏天，人们很容易就会犯困，因此影响了学习以及工作，很多人都在尽量的提起精神来，那么，提神醒脑的方法有哪些呢?
I have an entry.rb model and I\'m trying to make a semi-complicated validation. I want it to require one or more of the following fields: phone, phone2, mobile, fax, email or website. How would you wr
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