Aeroplanes carry passengers to various parts of the world in almost as many hours as it takes days to do the journey by other means.

老师，我看不出比较分句as it takes days to do the journey by other means.中必须省略的比较对应项(as many hours还是many hours)?

麻烦分析一下as分句的gap在哪里？as it takes days to do the journey by other means。似乎不缺成分，那么，gap呢？