We must thoroughly understand this.

对此，我们必须有足够的认识。

Do you thoroughly understand the code?

你真的把代码完全搞懂了？

We thoroughly understand each other, even if we don't always agree.

我们彼此非常了解，虽然有时候也有一些分歧。

When you live among people, we must respect and thoroughly understand them.

与外人相处，我们必须十分了解、尊重他人的一切。

It is vital that you thoroughly understand what erroneously happened to you.

你们彻底地理解错误地发生在你们身上的事情是至关重要的。