Sentence Study 4 为了获取流行病学的有效数据，我们同时还需要 至少六名宇航员轮翻上阵，持续不断地试验，来 获取零重力对宇航员生理和心理影响的数据并验 证对策的有效性。 Home Paraphrase: we also need at least six astronauts to take turns to work continuously to get medically reliable data on the bodily and mental effect of 0g on astronauts and the usefulness of the actions taken to overcome the effects.