一个盒子内装有只有颜色不同的四个球，其中红球1个、绿球1个、白球2个，小明摸出一个球放回，再摸出一个球，则两次都摸到白球的概率是____ 

根据句意及首字母提示完成单词

（1）My teacher is very f____，we all like her.

（2）My father is watering flowers in the g____ now.

（3）—Where were you b____?  —In a small city in Hunan.

（4）My son is 9 years old. He studies in a p____ school.

（5）The old man lived here 20 years a____.

① Where does she live? ____     A. It's on December 25th．

② How's the weather in December? ____     B. I ride a bike in the park．

③ What do you do at weekends?  ____     C. It's cold and dry．

④ When is the Christmas Day? ____     D. She lives in Beijing．

⑤ Who is he?____     E. He's Father Christmas．

氧气是我们身边常见的物质，以下关于氧气的叙述不正确的是