根据课文大意，在每个空格处填上一个合适的单词。

    Several days before July 28, 1976, many things happened in Tangshan. They were signs for an . But people lived there didn't think much of that. At 3:42 am that day, the earth began to shake, which almost all the city in fifteen terrible seconds. Many people, including workers and doctors, came to those who were under the ruins. Later that afternoon, another big earthquake hit the city. More people were killed or and more buildings down. Very soon the army sent a lot of soldiers to help, and teams were to dig out the trapped and to the dead. By and by things improved and the city began to breathe again.