根据光源的( )来划分，人工光源又可分为暖光源与冷光源两种。
A．物理原理
B．化学原理
C．色彩
D．视觉效果
参考答案：C
根据句意写单词。
1.My mother calls him brother and I call him______.
2.Her mother's father is her ______.
3.He is my father.I'm not his son.I'm his ______.
4.This is my father and this is my mother.They're my ______.
5.Peter is Bill's cousin,so Peter's mother is Bill's ______.
细菌接种环要求长度为（）
A.5～8cm
B.5～6cm
C.8～9cm
D.6～10cm
E.5～9cm
