为了掌握外语，我们必须下苦功夫。

We must work hard at a foreign language so as to master it.

我们必须在口语方面下苦功夫。

We must work hard at the spoken language .

注意力是智慧的门户。要得惊人艺，须下苦功夫。

Attention is the portal of wisdom. Get the astonishing skill, must be hard.

在50岁之前，他下苦功夫，临摹古代山水画大师的作品，打下了深厚的传统功力。

Before the age of 50, he had copied the works of many famous ancient Chinese landscape painters, which laid his solid traditional Chinese painting foundation.