It was a period of intense activity.

　　那是活動激烈的時期。

　　Economic activity often follows a cyclical pattern.

　　經(jīng)濟活動常常遵循周期性模式。

　　He watched for signs of activity in the house.

　　他注視著那所房子里的動靜。

　　The whole place was a scene of feverish activity.

　　整個地方都是一片緊張匆忙的景象。

　　He watched the house for signs of activity.

　　他注視著那所房子里的動靜。