肝硬化再生结节T2加权像表现低信号，因()
A．病灶内含铁血黄素沉着
B．病灶血管腔隙中含纤维间隔
C．病灶内钙化
D．A+B
E．B+C
参考答案：D
Perform Quality Control is the process of monitoring and recording results of executing the Quality Plan activities to assess performance and recommend necessary changes.（） are the techniques and tools in performing quality control.
①Statistical sampling
②Run chart
③Control charts
④Critical Path Method
⑤Pareto chart
⑥Cause and effect diagrams
A．①②③④
B．②③④⑤
C．①②③⑤⑥
D．①③④⑤⑥
转向费力，可能出现的原因是下面哪一个（）
A、工作泵严重内漏
B、油温太低
C、安全阀调整不当，系统压力低
