说明：  该LINGO程序的功能是：求出工程项目的收益的净现值和每道工序的最优开工时间，约束条件是紧前紧后约束，以及资源约束。。。
(The program' s function is LINGO: the project proceeds to derive the net present value of each procedure and the optimal start time constraints are tight after the former tight constraints, and resource constraints. . .)