______ the average age of the population increases, there are more and more old people to care for.
Unless
Until
As
While
Without the development of the Internet, Taobao and Tmall______$ 5.7 billion in sales on 11 November, 2013.
He was very nervous in the contest.Otherwise,he _____________ the first prize.
I didn’t know that he was a cheat, or else I ________________ him.
________ the present unemployment continue, the society would face a more troublesome situation.
I forget where I learned the saying, or I _____ it to you now.