如果是国际航班：（我没有坐过国内的航班）
在降落之前到达机上上空时
we are landing XXX airport shortly(or in 5-10 minutes).the cabin crew are collecting carpet and earphones now,please help to do so.
the temperature is XX degree.the weather is sunny/cloudy/windy...
快要到达跑道时：
cabin crew take a seat,we are landing now.
降落时：
please fasten your safe belt till the symbol light is off,keep you in seat and do not open overhead cabin till the flight is totally stopped thank you!