翻譯一些英語句子(中譯英)，有關(guān)鍵詞

【專家解說】：1 if you don't know the key to these problems,please don't hesitate to ask me about it. 2 as a matter of fact,nobody can hit over night without any efforts. 3 you'd better not rest your head on the table,it is high time that you got down to business.