注意：
a. 句首名词不能带任何冠词。 b. 句首是实义动词，其他助动词放在主语后。如果实义动词有宾语和状 语，随实义动词一起放在主语之前。 Try hard as he will, he never seems able to do the work satisfactorily. = Though he tries hard, he never seems… 虽然他尽了努力，但他的工作总做的不尽人意。
原因状语从句
比较：because, since, as 和 for 1） because 语势最强，用来说明人所不知的原因，回答 why 提出的 问题。当原因是显而易见的或已为人们所知，就用 as 或 since。
I didn't go, because I was afraid. Since /As the weather is so bad, we have to delay our journey.
让步状语从句
though, although 注意： 当有 though, although 时，后面的从句不能有 but，但是 though 和 yet 可连用 Although it's raining, they are still working in the field. 虽然在下雨，但他们仍在地里干活。 He is very old, but he still works very hard. 虽然他很老，但仍然努力地工作。 Though the sore be healed, yet a scar may remain. 伤口虽愈合，但伤疤留下了。 （谚语）
2） 由 because 引导的从句如果放在句末，且前面有逗 号，则可以 用 for 来代替。但如果不是说明直接原因，而是多种情况加以推断， 就只能用 for。
