－ Take one more pen. If your pen doesn’t work during the exam, you can use the other one.

－ OK, Mum. You are always_______.

A．grateful

B．useful

C．thoughtful

D．wonderful

人类行为可分为本能行为和（）

A.外显行为

B.社会行为

C.生物行为

D.遗传行为

E.能动行为