问题
多项选择题
下列不属于双代号网络图绘图原则的是( )。
A．网络图应只有一个起点节点和一个终点节点(多目标网络计划除外)
B．网络图中不允许出现重复编号的节点
C．严禁在箭线上引入或引出箭线
D．严禁网络图中工作箭线交叉
E．网络图中的箭线应保持自右向左的方向
答案
参考答案：D,E
搜题请搜索小程序“爱下问搜题”
下列不属于双代号网络图绘图原则的是( )。
A．网络图应只有一个起点节点和一个终点节点(多目标网络计划除外)
B．网络图中不允许出现重复编号的节点
C．严禁在箭线上引入或引出箭线
D．严禁网络图中工作箭线交叉
E．网络图中的箭线应保持自右向左的方向
参考答案：D,E
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| From Monday to Friday most people are busy working or studying, but in the evening and weekends they are free and __1__ themselves. Some watch television or go to the movies, others __2__ sports. This is decided by their own __3__ . There are many different ways to spend our __4__ time. Almost everyone has some kind of __5__, it may be something from collecting stamps to __6__ model planes. Some hobbies are very __7__, but others don't cost anything at all. Some collections (收藏) are worth __8__ of money, others are valuable (有价值的) only to their owners. I know a man who has a coin collection worth several __9__ dollars. A short time ago he bought a rare (罕见的) fifty cent piece which __10__ him $250! He was very happy about this collection and thought the price was all right. On the other hand, my youngest brother collects match boxes. He has almost 600 of them, but I wonder __11__ they are worth any money. Howeyer, __12__ my brother they are quite valuable. __13__ makes him happier than to find a new match box for his collection. That's what a hobby means, I think. It is something we __14__ to do in our free time just for the __15__ of it. The value in dollars is not important, but the pleasure it gives us is. | ||||
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