时间状语从句：连接词when，whenever, while，as，before，after，till，until，not…until，since, ever since , once, as soon as, the moment，the second, immediately，instantly，directly。
九种常见的状语从句及其常用的连接词
(1)时间状语从句：连接词when，whenever, while，as，before，after，till，until，not…until，since, ever since , once, as soon as, the moment，the second, immediately，instantly，directly, hardly…when，scarcely…when，no sooner…than；the first／second／last time，every time;
(2)地点状语从句：连接词where, wherever;
(3)原因状语从句：连接词because，,since，as, for; now(that);
(4)条件状语从句：连接词if，unless，as long as，so long as, as/so far as…(be concerned); suppose/supposing/supposed that; provided／providing that; on condition that;
(5)让步状语从句：连接词although，though，as，even if, even though, whether…or(not); no matter what／when／where／who; wherever，whatever，whoever, however；
(6)结果状语从句：连接词so that; so…that，such…that; with the result that；
(7)目的状语从句：连接词so that，in case，for fear that，lest唯恐, 以免；
(8)方式状语从句：连接词as, as if, as though, how；
(9)比较状语从句：连接词than，as／so…as; such…as, the same …as;