Scientists have to work hard to keep _____ with modern discoveries and developments.
________it is to throw snowballs at each other on the playground after snow!
The house rent is expensive. I’ve got about half the space I had at home but I’m paying ________ here.
She doesn’t suppose the prices will go down this week, _______?
I _______ Beijing in a few days. Do you know when the earliest plane ________?
Broad and Narrow Alleyin Chengdu is _______ tourist attraction that thousands of people