Mars is the fourth planet from the sun and it's the most like the Earth,but it's much __ than the Earth because it's farther from the Sun.
火星是距离太阳从近到远排位第四的,而且它是和地球最相似的,但是它比地球要（）得多因为它距离太阳更远.
farther在这里是far的比较级,意思为更远的.