David hated spending money. When he had to buy something in a shop, he always tried his best to knock down the price, even for the cheapest things. If he wanted to buy a bottle of orange, for example, and the shopkeeper asked for $2, David would say, "Make it $1.90 and I'll buy it." Sometimes the shopkeepers agreed to _ their prices a little. "What's ten cents?" they asked themselves. "If it makes this man happy, it won't hurt me very much." In this way David saved a few cents here and a few cents there, and by the end of the year he had saved several hundred dollars. One day he had a very bad toothache and had to go to the dentist. The dentist looked at the tooth and said, "This tooth will have to come out. It's too serious to save." "How much must I pay you to take out a tooth?" David asked. "Forty dollars," the dentist said. "How long will it take you to pull out the tooth?" he asked. "About two minutes," the dentist answered. "Forty dollars for two minutes' work!" he shouted, "That's robbery  ." The dentist smiled. "You're right," she said. "Thank you for telling me. I'll pull your tooth out very slowly. How about if I take half an hour?" David thought that two minutes was   _  .
too little time to pull out a tooth too little time to pay the dentist $40 too long to pull out a tooth too short for the dentist to finish the operation