他对英语语法有很好的掌握。

He has a good ___grasp of English grammar.

要胜任这个职位，你需要扎实掌握公司的软件工具。

To succeed in this role, you need a solid ___grasp of the company's software tools.

教授的讲座帮助我牢固掌握了复杂的经济学原理。

The professor's lectures helped me gain a firm ___grasp of complex economic principles.