Fill in the blank with the appropriate question tag.

One can't be too sure, ________?

can one

The correct answer is Option (1) - can one

So, the completed sentence would be: "One can't be too sure, can one?"

• The main clause is negative: “can’t”
• Rule: A negative statement takes a positive question tag
• Subject = one, so tag must also use “one”
• Auxiliary verb = can

So, correct tag = can one?