根据所给的中文写出单词。

     I like traveling when I am  _ 1__(有空的). This winter holiday, I have a  _2__(计划). I'm going to Hainan for my vacation.  _3    (虽然) I’ve been there  __4     (一次) , I still want to go there. And this time I want to __5   (呆在)there for five days. How can I get there? I’m going there by train because it's __6_  (迅速的，快的)and safe . Hainan is a good place to enjoy ourselves. It's __7   (闻名的) for its blue sea , clean beach and sweet fruits. I'm going sighting and swimming there. And I also want to  _8_ (骑)a bike , I will visit the   _9_ (整个的)island. I can't wait. I think I will never   _10 _ 

（忘记）this trip.

铜的密度是（）g/cm³