Manypeopledreamoftravelingintoouterspace．However，spend...
问题详情： Manypeopledreamoftravelingintoouterspace．However，spendingtoomuchtimeinspacemaycausehealthproblems，accordingtoNASA．That'swhyastronautsshouldn'tspendmorethansixmonthsontheInternationalSpaceStati...