In France it's rude ______ you're full, you should just say," It was delicious".    [ ]

A. to say            

B. to feel        

C. saying

人类行为是个复杂的系统，存在着各个不同的侧面，这体现了人类行为( )的特点。

A．适应性

B．动态性

C．可控性

D．多样性