《母婴保健技术服务执业许可证》、《母婴保健技术考核合格证》、《家庭接生员技术合格证》有效期为()
A.1年
B.2年
C.3年
D.4年
E.5年
参考答案:C
– Were you at school when I called you?
– Yes, I ________ in the library.
A. studied B. am studying C. was studying
胎姿势