根据短文内容回答问题
What do you think is the most common illness? Do you get ill sometimes? We are lucky to live now because there are lots of medicines to make people better．
The most common illness in the world is the cold．It often begins with a sore throat．Then you sneeze and your nose runs．You usually have a headache，too．Often you cough later．It's not a very bad illness but you can feel quite ill．
There isn't a cure(治愈)for a cold but you can take medicines to make you feel better．For instance aspirin(阿司匹林)can stop your headache．It is good to rest and to drink a lot of water，too．A doctor once said to me，“With the proper medicine a cold will last for seven，days．With no medicine it will go on for a whole week!”
Where does our medicine come from? A long time ago people knew that some plants made them feel better．They ate the leaves，the roots，the I fruit or the seeds of those plants．For instance the juice of lemons makes a sore throat feel better．
In modern times scientists have looked at these plants and found out which chemicals(化学物质)are in them．Many of our medicines today are made from those chemicals．
There are some illnesses which we can't cure yet．And nobody has found a cure for old age．But because of modern medicines most people now live longer than their grandparents．