It also awards me _____ opportunity to learn American culture at _____ first hand.

A．/; the

B．the; a

C．an; /

D．/; a

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