Of course, in this specific example we actually know the derivation of "B true" from "A ∧ (B ∧ C) true", but in general we may not a priori know the derivation.
当然，在这个特定的例子中我们实际上知道“B true”来自“A ∧ (B ∧ C) true”的推导，但是一般而言，我们不可以先验的知道这个推导。