求一篇英文的说明性演讲稿随便什么主题都可以~老师没说。大概在3分钟之内可以讲完~

求一篇英文的说明性演讲稿随便什么主题都可以~老师没说。大概在3分钟之内可以讲完~
求一篇英文的说明性演讲稿
随便什么主题都可以~老师没说。大概在3分钟之内可以讲完~

求一篇英文的说明性演讲稿随便什么主题都可以~老师没说。大概在3分钟之内可以讲完~
什么主题?
什么字数?
什么时候要?
PENICILLIN-Wonder Drug
Medicines have changed people's lives.If you open
up any medicine cupboard in the world,there is a high
probability that you will find penicillin,which has saved
millions of people's lives since they were invented.
Penicillin has helped increase the standard of people's
health.This bacteria-killing medicine is considered by
many to be one of the most important medicines in
contemporary society.It was discovered by a Scottish
scientist named Alexander Fleming in 1928.He noted
that mould had grown on a special transparent jelly
that had bacteria on it.He saw that the cells of the
bacteria were clear,which meant that they were dead
and that the mould had killed them.Fleming tried this
mould out on another bacterium and found that it killed
the bacterium too.He immediately thought that this
application might help in treating wounds and illnesses
caused by bacteria.He named the chemical found in
the mould 'penicillin' and tried to make it pure to be a
medicine,but was unable to do that.Fleming did not
give up.However,it was not until World War II that two
other scientists,Howard Florey(Australian) and Ernst
Chain (German-born English),managed to use new
chemical techniques to purify it.They were able to
produce it in large quantities.The new drug was
needed immediately because of the war,so mass
production started quickly.Due to the widespread use
of penicillin,many lives were saved during World War
II.It was a dream come true.If penicillin had not been
available,many people would have died from bacterial
illnesses or even minor wounds.Penicillin is also used
to treat other illnesses including pneumonia,an illness
that affects the lungs.So,althoughFleming discovered
penicillin,it was over a decade before someone else
turned penicillin into the great drug of the 20th
century.Penicillin is still widely used today,though
many types of bacteria are now resistant.
In 1945,all the three scientists,Fleming,Florey and
Chain,shared the Nobel Prize in Physiology or
Medicine for their work,and penicillin rapidly became
the powerful 'wonder drug' which saved millions of
lives.
说明青霉素的.