3)引导同位语从句关连词,除that外,还可以根据句义使用任何其它疑问代词或副词;而定语从句不可用what, how, whether等引导。
2.Counting begins tonight, but final official results are not expected until early next month.
not until…
这个句型从形式上看是否定句,但并非否定意思。until也可单独使用,表示“直到……为止”。
The doctor didn’t start the operation until the room was bright enough.
医生直到房间里的灯足够亮了,才开始做手术。
Not until I began to work did I realize how much time I had wasted.
直到我开始工作,我才认识到了我已蹉跎了几多岁月。
3.The French health ministry is promising major changes to regulations for licensing drugs after a report said up to 2,000 people died from a diabetes drug that should have been withdrawn from the market 10 years earlier.
这句话的主干是:The French health ministry is promising major changes to regulations...after后是时间状语从句。that should have been withdrawn是定语从句,修饰diabetes drug。should have been是与过去事实相反的虚拟语气,原本应该退出,但实际上没有退出。