1. The fundamental cause of his success is his hard work.
    他成功的根本原因是工作努力。

2. Their impregnable arguments are hard to rebut.
    他们牢不可破的论点很难被驳倒。

3. They tried hard to prevent the war.
    他们力图防止战争。

4. This kind of original painting is hard to procure.
    这种油画的原作是不易弄到的。

5. Their impregnable arguments are hard to rebut.
    他们牢不可破的论点很难被驳倒。

6. The recondite treatise is hard to understand.
    这篇深奥的论文很费解。

7. This slender tree bends when the wind blows hard.
    刮大风时，这棵细长的树会被吹弯的。

8. They felt weary after all their hard work.
    他们把所有的累活儿都干完

9. The hard work was worthwhile because I passed the exam.
    我考试通过了，所以刻苦努力还是值得的。

10. This made the driver following her brake hard.
    她这一停使得跟在后头的司机也来个急刹车。