其实这个句了也可以说没错误.但正式来说还是应该说“than A is”.
我们经常说“A is + 形容词比较级 + than B”,其实严格按照语法来说应该是 “A is + 形容词比较级 + than B is”才对.只是大家都经常把最后be动词省略了,所以几乎变成约定俗成的了,口语中都是这样子.又如我们经常可以听到He is better than me,其实正确地说应该是He is better than I am,再如I do well in maths than him应该是I do well in maths than he does.