since then是什么意思

“自从那时起”的意思。一般是要用现在完成进行时的，就是have+been+doing的结构,表示动作从过去的那个时刻开始一起在持续着。譬如：I have been waiting for the bus since then/since 5pm

since then用完成时态。意思是：自从那以后。示例：Since then, Michael has lived an unexceptional life 从那时开始，麦克尔就过着普通的生活。

短语

ever since then 自从那时起；从此之后

and ever since then 自那之后

But since then 但从那以后；但此后

since用作介词的意思是“从…以来，自从…之后”，其宾语常指过去的一个时间点，其含意通常指持续到说话时刻的动作或情况开始于什么时候。

since之后常接名词、动名词作其宾语，since then意为“从那以后”。

since用作副词表示“以前”时还可和long, ever连用。long since意为“好久以前”，not long since意为“就在不久前”，ever since意为“从那时起，此后一直”。

then本身是个过去的时间点，since

then表示从那个时间点到现在的情况，一般是现在完成时。

I

have

not

gone

there

since

then

I

have

been

there

since

then

It

is

30

years

since

then

所以99%的情况是不用过去时的，除非你写故事，故事里的时间发生在1980年，可以

It

was

20

years

since

then

这里的then当然是设定在1960年啦这只是特殊情况

since then 只能用现在完成时，“自从那时到现在为止”

from then on 可以用于现在完成时，过去式或者将来时，要看具体的语境

例如：He borrowed a book from the library three weeks ago He has kept it from then on

The final exams will ends on June 30 We'll begin our summer holiday from then on

Tom died in 1899, from then on his son had a bad life

since then是用作时间状语的副词性短语，既可以用在陈述句也可以用在疑问句，如：

　　Your life must have seemed very ordinary since then你的生活从那时起一定是非常平淡无奇的。肯定句

　　Your life can’t have seemed veryordinary since then 你的生活从那时起不会是非常显得平淡无奇的。否定句

　　Can your life have seemed very ordinary since then 你的生活从那时起会显得非常平淡无奇吗？疑问句

　　Since then I've been waiting on events 自那以后，我就一直在观望事情的发展。肯定句

　　Since then I've not been waiting on events 自那以后，我就一直都没在观望事情的发展。否定句

　　Have you been waiting on events since then 自那以后，你一直在观望事情的发展吗？疑问句

准确的来说，since是现在完成时态的标志词。而现在完成时态主要是指，过去某一动作持续到现在强调影响。轴距并非必须要用持续性动词也可以是短暂性动词，不过像while，必须引导持续性动词。