As it was a fine day,they decided to go fishing.为什么用as?为什么用as,而不是_英语解答

As it was a fine day,they decided to go fishing.
为什么用as?
为什么用as,而不是if

人气：255 ℃　时间：2020-06-07 18:55:57

解答

天气好是事实,这里是说,由于天气很好,所以他们决定去掉鱼
天气好不是假设的