What verb form is used in the sentence: "Can you believe how she _____ us talking to each other in French by the first month?"

In the sentence "Can you believe how she _____ us talking to each other in French by the first month?", the correct verb form is "made." This usage highlights an action in the past when she caused or prompted another action to occur, which in this case is "us talking to each other in French."

Using "made" emphasizes her influence or role in that situation, indicating she provided the opportunity or environment for this to happen. The sentence reflects a completed action since it references the first month as a specific point in time.

The other choices present verb forms that would not fit grammatically or contextually in this sentence. For instance, the past perfect form "had" suggests an action completed before another past action, which does not align with the structure focusing on immediate past influence. The present perfect "has" indicates an ongoing action or a state extending to the present, which doesn't apply here either. The past continuous "was" suggests a background action rather than the active causative role indicated by "made."