You can only be sure of_________ you have at present; you cannot be sure of something _____ you might get in the future.
---You may find the key to the maths problem on page 107. ---Ah, it’s so simple. I wonder why I ________ of that.
----You seem to have known Dr Smith for a long time.---- That’s true. ______ he joined our club six years ago.
----I don’t mind telling you what I know. ----You ________. I’m not asking you for it.
The Mid-Autumn Day, which is a day for family reunion in China, _____ on September 12th this year.
Three years ago in Beijing, my best friend, David, was hit by a car while riding a bike, _______ a terrible brain injury.