常用的质量统计方法有（）、排列图、因果图、相关图、管理图、调查表、分层法。
参考答案：直方图
What does the speaker mean a. People who throw dirt will be punished. b. People who throw dirt will meet resistance. c. People who throw dirt will lose justification and support. d. People who throw dirt will get dirty themselves.
下列氨基酸中，哪种是天然氨基酸（）
A.鸟氨酸
B.脯氨酸
C.瓜氨酸
D.胱氨酸
E.羟脯氨酸
