A 3G mobile phone, ______to be most useful and fashionable, is popular with some teenagers.
Parents________send their children to school when they reach six years old.
—I don't care what people think.—Well, you________.
I ________ use a clock to wake me up because at six o'clock each morning the train comes by my house.(2012·新课标全国)
We________finish it ahead of time, though it was such a tough task.
She was very brave.Even though she'd hurt her leg, she________go back alone.