In 1834, the clock tower in London was burned down. People planned to build a new clock which would be the biggest and best in the world. So the clock had to be big and keep very good time. The big clock was made in two years. Five more years later the tower was finished. Then people put the big clock in the tower, and made it ring out for the first time on July 11, 1859. In order to give the bigclock a good name, people held a meeting. Someone wanted to call it the Queen of Bells, and someone thought Victoria was good. At last, a man named Benjamin Hall stood up. He was a big man. Before he started to speak, someone shouted, "Why not call it Big Ben? "Everybody laughed and agreed with him. From then on, Big Ben became its name. And it also became a famous building of London. People all over the world write to Big Ben. They even send birthday presents--bottles of oil-to help keep Big Ben running. Big Ben is not only a clock but also a dear friend ofpeople. The phrase "keep very good time" means   _  .
have a good time show people the correct time keep running be made in time