液体渗透技术适应于检测非多孔性材料的（）。
A.近表面缺陷
B.表面和近表面缺陷
C.表面缺陷
D.内部缺陷
参考答案：C
腮腺囊肿的超声表现，哪一项是错误的（）。
A.内为无回声区
B.形态欠规则
C.多呈圆形
D.边缘整齐、界限清楚
E.后方回声增强
Where was it ______ you _______ our maths teacher?
A．where; came to
B．that; come across,
C．that; came across
D．where; come to
