听力原文： (29) Tile Golden Gate Bridge joins the beautiful city of San Francisco with its suburbs to the north. (26)Each day, about one hundred thousand cars cross the bridge, taking people to and from the city. More than half of them cross the bridge during the morning and evening rush hours. As a result, the trip is not pleasant.
Now, however, there is at least one group of happy commuters. These are the people who travel under the bridge instead of on it. They go to work by boat and enjoy it so much that most say they will never go by car again. (29)The boat they take is the large, quite, comfortable "Golden Gate". (27)Commuters can enjoy the sun on the boat. In the morning they can have breakfast in the coffee shop, and in the evening they can have a drink in the bar while they are looking at San Francisco's famous scene and the nearby hills.
The trip takes only thirty minutes and is not very expensive. And what's more, being on a boat seems to make people feel more friendly towards each other. Two commuters who met on the "Golden Gate" have already got married.
Because the boat has been so successful, there are plans to use other, still larger boats. There is also a plan for a high speed boat that will make the trip in only fifteen minutes. (28)Not everyone is happy about that. "A lot of people don't want to get the trip faster," said one commuter. "They feel that half an hour is just enough time to rest."
(33)

A. Because the trip takes as long as 30 minutes.
Because the bridge is too long.
C. Because the bridge is crowded with cars.
D. Because the drivers can't enjoy the beauty there.