开展产前诊断技术的《母婴保健技术服务执业许可证》每（）年校验一次，校验由原审批机关办理
A.一
B.二
C.三
D.四
参考答案：C
为避免筒体与端盖的磨损，在圆筒的内壁装设有波浪型的（），护甲对缝处有“X”型的闭锁栓互相啮合而成。
Tony often makes his sister _______, but this time he was made ______by his sister.
A．cry, cry
B．crying, crying
C．to cry, cry
D．cry, to cry
