そんなことは私にだってわからない、、イディオムです。7:35 how long can they keep this up? it's a great question. I don't know. Liz, your guess is as good as mine. この強敵緩和第3弾はいつまで続くのでしょうか?そいつはいい質問ですね。わかりません。あなたと同じく私にも全然わかりません。注;話者が聞き手と同じ考えだ、ということです。したがっていつもI don't knowになるとは限りません。
http://www.youtube.com/watch?v=QYHzyLrtvBY&feature=related 9:59 your guess is as good as mine. 何の意味か全然わからん。
http://www.youtube.com/watch?v=g8PWgunfAAM&list=PL_cf1NqxrDmR-BqV8x4fvzoN1vcHaycVi 1:07 if you're wondering why weed is allowed and hats are not, your guess is as good as mine. 大麻は許されているのに店内で帽子がかぶれない理由は、そんなこと私にもわかるわけがない。
http://www.youtube.com/watch?v=tufG0D_lxQs 3:38 your guess is as good as mine
http://www.youtube.com/watch?v=GLR6uglygFo 3:00 anybody's guess is as good as mine.
参考リンク
http://bridge-english.blogspot.com/2011/08/blog-post_1499.html 誰にもわからないを英語でなんと言うか?
練習問題解答
a-331 your guess is as good as mine
a-7485 your guess is as good as anyone's
b-0566 your guess is as good as mine
b-0708 your guess is as good as mine
b-2475 your guess is as good as mine
b-6225 your guess is as good as mine