临床资料：男，46岁，自述呛咳、胸闷、进行性呼吸困难两周余。CT：右肺转移癌，肺不张。

超声综合描述：坐位背部右侧胸腔扫查右肩胛线一右腋前线第8肋间以下可见大片状无回声区，深度7．0cm，距体表2．3cm，内透声清亮，无回声内见细长楔形中等回声区漂浮。

超声提示（）

A.右肺囊性占位

B.右侧胸腔包裹性积液右肺下叶不张

C.右膈下积液

D.右侧胸腔大量积液右肺下叶不张

A client seeks care for low back pain of 2 weeks' duration. Which assessment finding suggests a herniated intervertebral disk

A．Pain that radiates down the posterior thigh.

B．Back pain when the knees are flexed.

C．Atrophy of the lower leg muscles.

D．Positive Homans' sign.