她是一位优秀的老师——她真的精通她的领域。

She's an excellent teacher - she really ___knows ___her ___stuff.

她从不怀疑自己的能力。她确实精通她的东西。

She never doubted her own abilities. She ___knew ___her ___stuff all right.

要在这个行业成功，你真的需要精通你的领域。

To succeed in this industry, you really need to ___know ___your ___stuff.