* * 流血由少渐多,腹痛加重,宫口逐渐开大,有组织物堵塞于宫口:
A.不完全流产B.稽留流产C.难免流产D.先兆流产E.完全流产
参考答案:C
Robert is away. He _______ America since last week.
A.has been to
B.has joined a club in
C.has studied in
D.has become a manager in
数据库的实施主要包括以下四项工作:用DDL定义数据库结构,数据装载,编写与调试应用程序以及______。