Section DDirections: in this section you will hear a recorded short passage. The passage is printed in the test paper, but with some words or phrases missing. The passage will be read three times. During the second readings you are required to put the missing words or phrases on the Answer Sheet in order of the numbered blanks according to what you hear. The third reading is for you to check your writing. Now the passage begin.Welcome to the Public Bus System. Its bus network operates 365 days of the year and has （20）that can take you to your destination(目的地) quickly and easily.You can travel round the city for just （21）a day with Type-A bus tickets. Type-B bus tickets are even （22）.You can get on and off as many times （23）, so you can tour the city at your own pace.You can buy tickets at most newspaper stands.If you want to get （24）, call the office of the Public Bus System.