hard的副词还是hard；
hard
adj. 努力的；硬的；困难的；辛苦的；确实的；严厉的；猛烈的；冷酷无情的
adv. 努力地；困难地；辛苦地；接近地；猛烈地；牢固地
例句
Its pretty hard to explain.
这事很难解释清楚。
I find that hard to believe.
我对此感到难以相信。
His father was a hard man.
他父亲是个冷酷无情的人。
She was a hard taskmaster.
她是个严厉的工头。
I only succeeded through hard work.
我就是因为努力工作才成功的。
