what is "nerve agent" ? Yesterday ,when I read an English news about terrorism happened in British , I met a short sentence "nerve agent", I know the "nerve " is the part of body about mind , control ,and feeling . But agent , I only know it is a branch or people of some apartment , institution , or organization ,such as agent of CIA, agent of S.H.I.E.L.D. I do not know how to understand the meaning of "nerve agent ", so I have to look up it by E-dictionary. Finally , I got the meaning , the agent means some chemical ，medicine or drug . So nerve agent means nerver gas, a kind of poisonous gas which can damage nerve system . Some simple words have many means what I have nerve met.

Yesterday I wrote a passage. Yesterday I wrote a passage. Maybe it is so long that no one rectify it. So I deleted it today, and wrote short passage. maybe the long passage is not welcome.