一個東西是否安全是有個“濃度”的度在那裏的：若有毒物質的濃度很低，也是安全的。

來源: nWAY 於 2013-03-15 13:35:13 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

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