单选题 After several ______ attempts to send the missile into space, the spacecraft was finally launched successfully.
A. abortive B. difficult C. experimental D. preliminary

【正确答案】 A
【答案解析】(abortive流产的，失败的)。句意为；把导弹发射到太空中去的几次尝试失败以后，宇宙飞船的发射终于取得成功。B．difficult困难的；C．experimental实验性的；D． preliminary预备的，初步的。