The preposition 自从
We use the preposition 自从 to express phrases like “since...” or “from...”.
We should state the preposition 自从 
before the adverbial modifier of time to indicate when the action began. It may be either a specific time or some event in the past.
before the adverbial modifier of time to indicate when the action began. It may be either a specific time or some event in the past.Scheme
自从
when
action
Examples
自从2000年
Since 2000
zìcóng èr líng líng líng nián
自从他们生孩子
Since they had a child
zìcóng tāmen shēng háizi
These sentences may have either one or two subjects.
If there is only one subject in the sentence, it may be stated either before 自从 or after the adverbial modifier of time:
Examples
她自从离开学校就再也没见过他
She hadn't seen him since she graduated from high school
tā zìcóng líkāi xuéxiào jiù zài yě méi jiànguò tā
自从今天上午我什么都没做
I haven't done anything since this morning
zìcóng jīntiān shàngwǔ wǒ shénme dōu méi zuò
If there are two subject in the sentence, we should state the first subject after 自从 and state the second subject after the adverbial modifier of time.
Examples
自从她丈夫去世后，她老了许多
Since the death of her husband, she has aged a lot
zìcóng tā zhàngfu qùshì hòu, tā lǎo le xǔduō
自从我上次见到你后，你又见长了！
You've grown a lot since I saw you for the last time!
zìcóng wǒ shàng cì jiàn dào nǐ hòu, nǐ yòu jiàncháng le
After the adverbial modifier of time. we can use words such as:
后 or 以后
起 or 开始
以来
or 以后
起 or 开始
以来 Examples
自从她走后，他一直不停的工作
Since she left, he has been working non-stop
zìcóng tā zǒu hòu, tā yìzhí bù tíng de gōngzuò
自从毕业以来她一直找工作
She has been looking for a job since she graduated
zìcóng bìyè yǐlái tā yìzhí zhǎo gōngzuò