The "threshold to enter the threshold" effect refers to the phenomenon of increasing the possibility of accepting a larger request before making a larger request. According to the above definition, Which of the following items that meet the "threshold threshold" effect are (). ['A survey shows that the proportion of residents in a city willing to donate to save endangered species is 48%, and if people are asked to sign the petition to save endangered species (almost everyone will agree to sign), then they are invited to donate and are willing to donate Increased by 20%.', 'The savvy merchants often set the price far higher than the actual price when selling the product, and then let the customer accept a relatively low price when bargaining. In fact, this low price is still higher than the price that the product should be. But customers are always happy.', 'A laptop of a certain brand has a low market share due to the low-cost performance. Manufacturers have formulated a promotional plan for this. When buying this laptop, they will receive a mouse, mp3 and USB flash drive. As a result, the sales of this laptop A substantial increase in volume.', 'An enterprise successfully developed a whitening toothpaste that removes smoke stains, and has been well received by the market because of its good effect of removing smoke stains. The company has launched several whitening kinds of toothpaste with different tastes while it is hot. Products are slightly improved, but still, become bestsellers.']