听力原文： Two powerful car bombs have exploded in a crowded part of San Salvador. Two boys were injured, one of them seriously when he was hurled across the street by the force of the explosion. (7)Shooting is reported to have broken out shortly afterwards. No one has claimed responsibility for planting the bombs, but eyewitnesses say the car had been left there by two women. A correspondent for the BBC in San Salvador says the incident is bound to heighten tension in the run-up to next week's election to National Assembly. Some hours earlier there were violent street disturbances in San Salvador when (8)hundreds of demonstrators protested against the detention of a leading trade unionist Mr. Wudato Santallo. What happened shortly after the explosion?