phr. Chinese is difficult, but I will try hard (in learning the language).
phr. As long as you study hard, you certainly will learn Chinese well.
phr. My boss works very hard.
phr. He deserves the success for his hard work.
phr. Keep at it, don't give up!
phr. keep on trying hard, keep making great effort
phr. The reason why he achieved such good grades is that he has always worked hard.