The bike-sharing schemes are aimed to __________ citizens to choose a healthy and green approach to solving the lack of public transportation.

Are you guys ready for “The Campus Singers Competition”?—Sure！Since we are young, try it, _____ we will regret!

I’m sorry to have kept you waiting.—____, Bill.

Didn’t your brother ___ go to school by bike —Yes, he did. But he __ walking to school now.

Don’t put off ____ to the doctor when you are ill.