---What _____ useful book! And ______ book is popular with students.A. a, a B. a, the C. the , the
---Will books be on paper in 100 years?---_______. They will be computers.
---Mary, how much did you ______ the new watch?---300 yuan.
---Linda, how is your physics project _______?---Very well. I’ll finish it tomorrow.
I hope _______more robots to help people in the future.
---If there are _____people driving, there will be ______air pollution.---Yes, the air will be fresher and cleaner.