【单选题】
The common cold is familiar to everyone. People often catch cold in __31_ winter
or spring. They may __32_ catch cold at other times __33_ the year.A、person with
__34_ bad cold usually buys some __35_ of medicine. Pharmacies have many __36_ for a
colD、However， doctors __37_ that these medicines do not __38_ very much. They that
__39_ person with a bad cold __40_ stay in bad， keep warm， and drink a lot of water.
In 1928 anEnglish doctor was working in his laboratory in London hospital. The
doctor‘s name _41_Alexander Fleming. One day he _42_ a tiny bit of mold (黴) _43_ a
dish that he was _44_ in his work. He started _45_ throw the mold away. Then _46_
noticed that it seemed unusual. He _47_ the mold and studied _48_ for a long time. He
_49_ that it could kill germs. He _50_ it penicillin.