What warning does the professor give when he talks about the man who lives on the mountain

What warning does the professor give when he talks about the man who lives on the mountain？

A．Avoid placing characters in remote settings

B．Avoid having more than one major character

C．Avoid using people as models whose lives are unusual

D．Avoid making characters into stereotypes

此题为多项选择题。请帮忙给出正确答案和分析，谢谢！