关于英语形容词的几个问题1.Bob won the long jump.he jumped _________ all

关于英语形容词的几个问题
1.Bob won the long jump.he jumped _________ all the others.
a.longer than b.aslongas c.longest of d,longest in 答案是C选项.
为什么是c?不是A?c,d有什么区别?
2.dr li was so [busy surfing on]the internet可不可以改成busy on surfing?dsfKjugg>>?/