短效避孕药的禁忌证不包括
A．慢性肝炎B．哺乳期C．月经稀少D．血栓性疾病E．宫颈糜烂
参考答案：E
Robert wishes that he ________ business instead of history when he was in university.
A．studies
B．studied
C．has studied
D．had studied
区分有光和无光切片主要的依据是根据聚合物（）。
A、粘度
B、二氧化钛含量
C、色相L值
D、色相b值
