Don't act like ________.

• A. you know everything
• B. you know nothing
• C. you know a lot
• D. you know less

Answer: (A)

The idea here is about natural English for a negative command using “act like.” The most natural completion is “you know everything,” giving the familiar warning: “Don't act like you know everything.” This expresses a clear admonition against pretending to have all the answers and keeps the tone strong and common in everyday speech.

The other options don’t fit as well. “Don’t act like you know nothing” is grammatical but sounds like a different kind of message—more about downplaying knowledge than warning against overconfidence. “Don’t act like you know a lot” is possible, but it softens the admonition and isn’t the usual sharp warning people intend here. “Don’t act like you know less” is awkward and incomplete without a clear comparison, so it’s not how this sentiment is typically expressed.