A method of precise levelling under unequal back-and fore-sightlength is studied and presented in this paper.
本文研究提出了在前后视距不相等的情况下进行精密水准测量的方法，分析了具体的实测方案。
2
There certainly were tears in his when, at length, having watched the train out of sight, he turned round.
而最终当他目送列车驶出视线，转过身时，他眼里也噙满了泪。
3
The boat that now arrived, assured by the answering signal that all was well, soon came in sight, white and silent as a phantom, and cast anchor within a cable's length of shore.