Scientists discovered that atoms of some substances are radioactive. This means that they

are unstable and can be split. The chain of splitting atoms releases great destructive energy and it was this discovery which led scientists to develop the idea of an atomic bomb. The American government secretly worked to produce such a bomb and the first version was much more powerful than anyone had thought.

By this time, the World War II had ended in Europe. But the Japanese refused to surrender, the Americans decided that by dropping an atomic bomb on Japan, they could end the war quickly and save more of their soldier’s lives.

Soon after midnight on 6 August 1945, a bomb was dropped on the city of Hiroshima, a civilian target. No warning was given and there was total devastation. Almost all the buildings were destroyed and more than 100000 people died or were horribly wounded.

The Japanese military still did not want to surrender so three days later, the Americans dropped a second atomic bomb on the city of Nagasaki, killing 45000 people. The Japanese government was discussing ending the war when they heard the news of Nagasaki. Finally, they surrendered and the World War II came to an end.

At first, the scientists who had built the bomb were pleased that it had helped to end the war. However, many would come to realize that they had helped to create the most terrible weapon known to man.

The first atomic bomb ______.

A．was less powerful

B．was dropped in Nagasaki

C．was a failure

D．was tested in desert