SECTION B INTERVIEW Directions: In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Questions 1 to 5 are based on an interview. At the end of the interview you will be given 10 seconds to answer each of the following five questions. Now listen to the interview. 听力原文：Mr. Jones: What materials were used for road surfaces during the last century? Engineer: Usually they were gravel and macadam. Tars and asphalt were originally used only as coverings, but later they were used as binders and finally as hot mixtures. Mr. Jones: Concrete is a modern material as far as road - building goes, isn't it? Engineer: Relatively speaking. But you might be surprised to know that a concrete road was built as early as 1893 in Ohio. But it was only 5 miles long. More extensive projects were not undertaken until much later, around 1912 or 1913. Mr. Jones: This was because of the increase in traffic? Engineer: That's right. Especially in the use of heavy tracks. More rigid pavements, such as concrete and brick, became a necessity. For light traffic, though, water-bound macadam, gravel, sand clay, and bituminous mixtures were still used. Mr. Jones: What are turnpikes usually made of? Engineer: Turnpikes are usually made of reinforced concrete about 8 to 10 inches thick, placed on a granular sub-base, which in turn is placed on a well - tacked earth subgrade. Of course, the construction depends a lot on the local climate, rainfall, soils, and so on. Mr. Jones: How do you mean--climate? Engineer: Frost is one of the main problems. For example, in Maine, where frost is quite frequent, the typical turnpike construction is a thin top layer of asphaltic concrete on a base layer of sand and gravel placed on a 36 - inch, frost - free, granular sub - grade. Mr. Jones: What is the width of these roads? Engineer: The early two - lane roads were about 20 feet wide. But with higher automobile speeds, the width requirements increased greatly. To give you an example, the Pennsylvania Turnpike has two 12 - foot lanes in each direction, separated by a median 10 feet wide. On each side there is a 10 - foot stabilized shoulder, marking a total width of 78 feet. The New Jersey Turnpike averages 100 feet in width, with three lanes in each direction. Mr. Jones: I guess wider roads are being built every day. Engrneer: That's right. Sometimes you think that, no matter how good a road you build, the speed and weight of vehicles will always be one step ahead. What materials were not used for road surfaces during the last century?