为敷设经纬仪导线，在选点时应考虑哪些问题？
参考答案：为敷设经纬仪导线，在选点时应考虑以下五个问题：
（1）导线点应选在地势较高，视野开阔的地点，以便于施测周围地形。
（2）导线点应选在土质坚实处，便于保存标志和安置仪器。
（3）相邻两导线点间要通视良好，地面平坦，便于测角和量距。
（4）导线点应有足够的密度面且分布要均匀。导线边长要大致相等，相邻边长不应悬殊过大。
（5）在公路测量中，导线应尽可能接近线路位置。
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| It was Tom's first visit to England, and he was looking forward to his first journey on London's Underground Railway. And against his friends' 1 , he was determined to travel 2 . He entered the station shortly after five o'clock in the afternoon. This is a 3 time to travel in London, 4 crowds of people go home from work at this hour. He 5 to join a long line of people waiting for tickets. When at last his 6 came, he had some difficulty in making himself understood by the ticket seller. 7 , he got the right ticket in the end and by asking people the 8 , he also found the right platform. It was 9 with people. He did not 10 to get on the first train, but he was able to move nearer to the platform so as to be in a better 11 to get on the next one. When this train came in, Tom was 12 forward onto the train by the 13 of people from behind. The doors closed and the train moved off. He was unable to see the 14 of the stations where the train 15 , but he knew that the station he wanted was the sixth 16 along the line. When the train reached the sixth station, Tom got off, feeling 17 that his journey had been so easy. But he suddenly realized that he had come to a station he had never 18 . He explained his 19 to a man who was standing on the platform. With a 20 on his face, he told Tom that he had caught a train going in the opposite direction. | ||||
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