A clear statement of the goal and scope of a research project is a useful reference point.研究项目有一个明确的目标和范围说明是很有用的参照点。Lee's case will be the reference point for lawyers in tomorrow's trial.李的判例将成为律师在明天庭审时的参考依据。The usual convention is to choose the reference point at infinity.通常的做法是在无穷大处取一个参照点。