时间状语从句什么时候用逗号
问题描述：
时间状语从句什么时候用逗号
例句Film has a much shorter history,especially when ___ such art forms as music and painting.
什么情况下时间状语从句在主句之后要用逗号,能结合例句帮我扩充一下这方面知识
答
正选答案compared to
在时间/条件状语从句中可以省略相同的主语（或做主语的It）以及谓语动词中所含的be（含其变形）.所以这里when compared to such art forms as music and painting=when film is compared tosuch art forms as music and painting,这样看来很明显答案是compared to.如果还有其他疑问,可以去“状元365”提问.