The most horrible thing is 'don't know "these three words.语法

The most horrible thing is 'don't know "these three words.这句 i don't know the meanings 还是meaning of these words.meaning到底 You know, I one's whole life is the most happy thing, t 英语翻译.when you are 45,the number of words you know is three t The most upset thing is that you don't understand me. The most important thing for learning English is:"Don't be a I don’t know the reason why he said these words.里面的why引导的从句是 The scary thing about them is that you don't know what they 英语翻译The scariest thing about distance is that you don't know 1,I don't know ( )these cars is the best.A.which 1.I don't know＿＿these cars is the best. Learn the words that you don't know.