The traditional view is _____ we sleep because our brain is “programmed” to make us do so.
_______in the city for thirty years, the old man moved back to the countryside.
The woman scientist was so busy that she could hardly_______time to her children.
On Feb. 6, Xi’an-Zhenzhou High Speed Railway,___________first high-speed railway in_______West China, was put into operation.
I advised you _____ drink water that isn’t ______ any more.
— ________? —No, you have to pay for them.