30． Scientists overcame much difficulty they had that technological problem they finally could send the manned spaceship up into space. A. to solve; until B. solving; before C. to solve; before D. solving; until 【查看更多】
题目列表(包括答案和解析)
Scientists overcame (克服) much difficulty they had _____ that technological problem _____ they finally could send the manned (载人的) spaceship up into space.
[ ]
A. to solve; until B. solving; before C. to solve; before D. solving; until
