Teacher:In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.
Teacher: Now, understand the problem? Solve this instance: Counterfeit banknote detection pens are used to detect counterfeit Swiss franc, euro and United States banknotes, amongst others. Typically, genuine banknotes are printed on paper based on cotton fibers and do not contain the starches that are reactive with iodine. When the pen is used to mark genuine bills, the mark is yellowish or colourless.
Student:
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