1 . ______________ (考虑到低重力对人体的这些消极影响), we discipline ourselves to do at least two hours of exercise every day. (根据汉语提示完成句子)

2 . ________ (如果没有重力), there would be no air around the earth. （根据汉语提示完成句子）

3 . Afterwards, he had the feeling of _____ (高飞） into the sky ____ ____ （因为）zero _______( 重力） .