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.

问题描述:

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.

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