题目内容
The astronauts found that ______ the spaceship went further and further into space, it became more and more difficult to control its own movements.
A. if B. till C. as D. while
C
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题目内容
The astronauts found that ______ the spaceship went further and further into space, it became more and more difficult to control its own movements.
A. if B. till C. as D. while
C