(2013·北京卷) Hurry up! Mark and Carl us.
Prices____ all the time and no one knows when they stable.
I think everyone should donate blood _____ he is healthy because that’s a citizen’s responsibility.
Mr. Smith has promised that all of us will pass the exam, so it ____ so difficult as you imagine.
I know that you’ve given me a rise in my pay, but I still think it’s enough for what I’ve done for your company.
The value of life lies not in many days we live, but in ____ use we make of them.