Stopreadingforaminuteandthinkaboutwhatyouseewhenyoulook...
问题详情：Stopreadingforaminuteandthinkaboutwhatyouseewhenyoulookupattheskyonaclearnight.Youprobablyseemanystars.Longlongago,farmerswatchedsomestarstoknowwhentoplanttheircrops.Travellersdidsotofindtheir...