"You should act like an adult"
"Don't behave like a fool"
"What makes her do this way?"
"The dog acts ferocious, but he is really afraid of people"
"She carried herself well"
"he bore himself with dignity"
"They conducted themselves well during these difficult times"
"The children must learn to behave"
You must behave yourself.
你必须要表现得像你自己。
He is now better behaved.
他现在表达好多了。