At what point do the bread and wine become the true body and blood of Christ?

The bread becomes the body of Christ when the words of consecration complete the sentence, i.e., when the object “body” (modified by the adjective “my”) completes the subject “This” and the verb or predicate, “is.” Once the thought is articulated: “This is my body,” the change takes place. The same goes for the wine becoming his blood. Sister told us that knowing the parts of speech would help us in the future—Sister scores again!