He studies harder than I.

他比我学习更努力。

youdao

He studies harder than one year before.

他学习比一年前更加努力了。

youdao

I don't believe he studies harder, does he? Does he?

我相信他不会努力学习的，会吗？

youdao

And in retrospective studies, he says, it's harder to control for common risk factors-- such as diet-- that might contribute to both prostate cancer and heart problems.

CNN: STORY HIGHLIGHTS

He still says that, if anything, those previous studies made the current result harder to believe.

FORBES: Provenge