常用的二氧化碳气是一种惰性气体,对化学性质活泼易与氧起反应的金属,是非常理想的保护气体。
参考答案:错
声门区喉癌放疗选用射线的最佳能量是()
A.深部X线
B.钴-60γ线或4MV直线加速器X线
C.8~10MV直线加速器X线
D.大于10MV直线加速器X线
E.电子束
A project management technique that is currently in widespread use is the (71) . The purpose of this technique is to detail, in hierarchical fashion, all of the activities that are required to meet project objectives. There are some special activities called (72) , which are events that signify the accomplishment or completion of major deliverables during the project. Most system development methodologies also provide (73) , whose purpose is to contain the various pieces of relevant information - feasibility assessments, schedules, needs analysis, and so forth - in a single place so that they can be presented to project clients and other related parties. Several types of important network diagrams are used in project management. (74) was developed to make clear the interdependence between project tasks before those tasks are scheduled. (75) offers the advantage of clearly showing overlapping tasks.
A.Network Diagram
B.CPM
C.Gantt chart
D.PERT