给下列单词归类。

(l)squirrel (2)arm (3)bag (4)bear

(5)black (6)body (7)dog (8)coffee

(9)white (10)monkey (ll)yellow

(12)leg (13)foot (14)sharpener

(15)crayon (16)Coke (17)water

(18)hamburger (19)tea (20)brown

颜色类：                              

器官类：                              

食品类：                              

文具类：                              

动物类：                              

何者是结膜炎常见病因（）

A.微生物感染

B.物理刺激

C.肺结核、梅毒等全身疾患

D.化学损伤

E.免疫性病变