以下对牙槽突裂的描述正确的是：（）

A.由于上颌突与球状突融合障碍所致

B.多数发生于上颌尖牙和侧切牙之间

C.治疗采取髂骨骨松质植入，封闭裂隙

D.植骨时间在上颌骨发育完成后即可进行

E.将影响牙胚的数目、位置以及牙形

The (71) is a general description of the architecture of a workflow management system used by the WFMC, in which the main components and the associated interfaces are summarized. The workflow enactment service is the heart of a workflow system which consists of several (72) . In a workflow system, a process is specified using the process definition tool. Usually, processes are defined in terms of a (73) , which consists of (74) indicated using a circle, and (75) shown as a rectangle. These two components can be linked by means of a directed arc.

（74）处填（）。

A．resources

B．places

C．positions

D．conditions