Fractional unemployment is best described as:（）

A. from normal labor turnover.

B. from changes in the skills needed to perform jobs.

C. due to fluctuating unemployment over the business cycle.

肺癌肺外综合征最常见的是（）

A.肥大性肺性骨关节病

B.肌病和神经综合征

C.高钙血症

D.Cushing综合征

E.周围神经病变