Adopting the space-group extinction rule and simulating the electron diffraction pattern with computer, this paper proposed a new method for selecting the reduced quadrangle.
引入空间群消光规律，用计算机模拟电子衍射图，提出选取约化四边形的新方法。
2
Alan Boss is the chairman of a group for outer space research.
艾伦·博斯是一个外层空间研究小组的主席。
3
Within a short space of time a group of complete unknowns had established a wholly original form of humour.