4.Since coal contains fewer hydrogen atoms than oil,then have to add some extra hydrogen to the gas.
问题描述：
4.Since coal contains fewer hydrogen atoms than oil,then have to add some extra hydrogen to the gas.
1.此处since引导原因状语从句?
2.请挑重要的简要地说下since的用法
答
1. 你的说法很对.
2. since所加的原因状语从句一般放在主句之首,表众所周知的原因,有时翻译成"由于/既然"更准确.
3. 此外since还可以做adv/prep/conj,较多出现完成时态.请看例句:
I've lived here since.自那以后我就一直住在这儿.
I've lived here since 1998. 自1998年以来我就一直住在这儿.
It is/ has been8 years since I moved here.自从我搬到这儿来已经8年了.
8 years passed since I had worked there.自从我不在那儿工作以来已经8年过去了.