超声墨菲氏征
参考答案：
急性胆囊炎病人做超声检查时，将探头压迫胆囊体表区触痛加重，探头深压腹壁接近胆囊底部瞩病人深呼吸，触痛加剧并突然屏住气不动。
The opportunity to take advantage of the downward pressure on stock prices that result from end-of-the-year tax selling is known as the:（）
A. January anomaly.
B. December anomaly.
C. end-of-the-year effect.
简述概念形成的条件。
