n.[U]

1. 行为，举止；态度
   He was on his best behavior.

   他表现极好。

2. （机器等的）运转状态，性能
   The aircraft's behavior was satisfactory on its first test flight.

   那架飞机在第一次试飞时运转情况令人满意。

3. （事物的）反应，变化；作用