苯丙酮尿症的病因是（）。
A.膜转运异常
B.合成酶缺乏
C.羟化酶缺陷
D.转移酶缺陷
E.酪氨酸酶缺乏
参考答案：C
The quality management plan provides input to ______ and must address quality control(QC) , quality assurance(QA) , and continuous process improvement for the project.
A．the overall project management plan
B．the WBS
C．the project scope
D．external stakeholders
针对社区内逃学青少年开展社区综合服务，属于青少年社工（）的层面。
A、微观
B、中观
C、系统
D、宏观
