Complete the sentences with the given words in their proper forms (用括号中多给单词的适当形式完成下列句子。每空格限填一词)
1. From the _____ floor of the hotel you can have a good view of the town. (nine)   
2.The Qingming Festival has already become a _____ holiday in China. (nation)   
3. Nowadays more and more people like wearing _____. (scarf)   
4. My younger sister looked ______ because she lost her favourite toy. (happy)   
5. As a student, we should know the ______ of learning English. (important)   
6. It's the _____ time that Mary has been late for the school this week. (two)