根據(jù)下列短文，根據(jù)其內(nèi)容寫一篇60詞左右的內(nèi)容概要。
    Strange things were happening in the countryside in northeast Hebei Province.For three days the water in the village wells rose and fell，rose and fell.Farmers noticed that the well walls had deep cracks in them.A smelly gas came out of thecracks.In the farmyards，the chickens and even the pigs were too nervous to eat.Mice ran out of the fields looking for places to hide.Fish jumped out of bowls and ponds.At about 3：00 am on July 28.1976，people saw bright lights in the sky.The sound of planes could be heard outside Tangshan even when no planes were in the sky.In the city，the water pipes in some buildings cracked and burst.But the one million people of the city，who thought little of these events，went to bed as usual that night.
    At 3：42 am everything began to shake.It seemed that the world was at an end！Eleven kilometers directly below the city the greatest earthquake of the 20th century began.It was heard Beijing，which is one hundred kilometers away.One-third of the nation felt it.A huge crack that was eightkilometers long and thirty meters wide cut across houses，roads and canals.Steam burst from holes in the ground.Hard hills of rock became rivers of dirt.In fifteen terrible seconds a large city lay in ruins.Two-thirds of the people died or were injured during the earthquake.Thousands of families were killed and many children were left without parents.The number of people who were killed or injured reached morethan 400.000.
    But how could the survivors believe it was natural？Everywhere they looked nearly everything was destroyed.All of the city's hospitals，75% of its factories and buildings and 90% of its homes were gone.Bricks covered the ground like red autumn leaves.No wind，however，could blow them away.Two dams fell and most of the bridges also fell or were not safe for traveling.The railway tracks were now useless pieces of steel.Tens of thousands of cows would never give milk again.Half a million pigs and millions of chickens had died.Sand now filled the wells instead of water.People were shocked.Then，later that afternoon，another big quake shook Tangshan.Some of the rescue workers and doctors were trapped under the ruins.More buildings fell down.Water，food，and electricity were hard to get.People began to wonder how long the disaster would last.
All hope was not lost.The army sent 150.000 soldiers to Tangshan to help the rescue workers.Hundreds of thousands of people were helped.The army organized teams to dig out those who were trapped and to bury the dead.To the north of the city，most of the 10.000 miners were rescued from the coalmines.Workers built shelters for survivors whose homes had been destroyed.Fresh water was taken to the cityby train，truck and plane.Slowly，the city began to breathe again.