It's running after a cat.
在追一只猫。
新概念英语第一册
Lesson 31 Where's Sally
📚 句中词汇解析
从本句中提取的重要词汇
n. 跑步;运转;流出;
adj. 跑着的;流动的;连续的;操作中的，运转着的;
v. 跑;运转(run的ing形式);
"He kept up a running commentary on everyone who came in or went out."
他不断地对上下场的每一名队员进行解说。
近义：march, operation, race, run, working, footrace
反义：lagging, leisurely, phlegmatic, poky, slowish, sluggardly