Task: Question Answering
Input (English): Background Paragraph: A catalyst is a substance that increases the rate of a chemical reaction.  A catalyst is a substance that increases the rate of a chemical reaction. The presence of a catalyst is one of several factors that influence the rate of chemical reactions. (Other factors include the temperature, concentration, and surface area of reactants.) A catalyst isn’t a reactant in the chemical reaction it speeds up. As a result, it isn’t changed or used up in the reaction, so it can go on to catalyze many more reactions. 
Story: Henry and Tiffany are performing chemical reactions in their high school chemistry class. Henry performs his reactions with the use of a catalyst. Tiffany performs the same reaction with no catalyst present. 
Question: Could Tiffany change other aspects of her reaction besides adding a catalyst to influence its rate, yes or no?
Output (English): yes.