涡流探伤中。差动式探头的优点是什么？
参考答案：
优点：
1、信号不因温度变化而引起漂移；
2、对探头的敏感度比绝对式探头低。
Which is WRONG about uterus （）.
A．it lies in the center of pelvic cavity
B． it lies between the urinary bladder and the rectum
C．neck of uterus is totally surrounded by vagina
D．there are uterine tubes on its two sides
E．inferior end lies in the vagina
铸铁模破损的部位是铸铁模强度（）部位。
A.最差
B.最好
C.任何
