根据句意填写单词使句子完整。

1.  In order to protect the environment, we aren't supposed to throw   __       about.

2.  I'm standing ______ the window to watch the snow.

3.  I don't think that your skirt is       __ for the party.  It's a barbecue.

4.  The panda is the ______ of China.

5.  I seldom write a letter to friends but I often       __   them on the Internet.