听力原文：The Robinsons were driving through Port Merlin Road when they heard a loud explos

听力原文： The Robinsons were driving through Port Merlin Road when they heard a loud explosion. At first, they thought it was the noise of a plane. But, before long, they saw smoke rising a few blocks away and a little further on they came upon a crowd in the street and men with armbands directing the traffic. The way ahead was blocked and they were in a one way street, so they tried taking a short cut down a side street and soon found themselves in a bad traffic jam. The car in front of them stopped and couldn't start again. So Mr. Robinson helped the driver to push it out of the way.

In the meantime, two fire engines as well as ambulances and police arrived and the ambulance men began looking for victims among the debris. The police put up a barrier with a notice across the street leading to the building, which was badly damaged. They were also trying to stop sightseers from getting near. Two of the ambulance man heard noises while they were searching. It sounded like someone knocking, m they took tm-ns clearing away the bricks to get at the person under the floor beneath them. In the end, they succeeded in rescuing him.

Some of those who had narrow escapes were interviewed by press reporters. Apparently the explosion had been mused by a leaking gas pipe and it looked as if the firm which had recently fitted the pipes was responsible for the accident.

(31)

A．An automobile collision.

B．An air crash.

C．The noise of a crowd.

D．An explosion.