题目内容：

there are many people in the park in the morning A exercising B to exercise
填充在people和in之间

优质解答

There are many people (A、exercising) in the park in the morning.
早上有很多人在这个公园里锻炼.
there be+主语+doing,有某人在做某事.这个句型要填动词的ing形式.