As there are so many people about,the dogs have to be kept in enclosure.为什么这里会出现逗号．

题目

As there are so many people about,the dogs have to be kept in enclosure.为什么这里会出现逗号．

答案

因为前面有连词as,所以这两句和起来表示因果关系的复合句.
因为这里有这么多人在附近,狗应该被关起来