根据句义每空填上一个适当的单词：
1.The———flag of P.R China is the Five-Star Red Flag.
2.There are many_______and tunncls along the railroad.
3.The River Seine(塞纳河)flows ________Paris.
4.They plan to send another satellite into________.
5.The plan is flying at an__________of 8000 meters.