眼睛能辨别背景上的对象，必须具备两个条件：（），或者在亮度上有一定的差别。
参考答案：对象与背景颜色不同
Although Tom did not actually get the best scores on every single test, ____________his high scores on the psychological tests____________finally won him his position as the best pilot.
A．it is; which
B．it was; that
C．it has been; that
D．it was; where
6岁男孩，右腹股沟肿物2年，于平卧时消失，站立时出现，哭闹时更加明显，用手可回纳入腹腔，透光试验阴性，可能诊断是（）
A.右侧精索鞘膜积液
B.股疝
C.腹股沟直疝
D.腹股沟斜疝
E.右侧隐睾
