--Is it _____ pen? --Yes. It' s ______ orange pen. A a; a B. an; an C. a; an D. an; a
--- How cool the iPhone5 is ! ---In our shop it_____ very well now. Get one before it________out.
I do not doubt ________ win in the race.
--- Do you know much about the city? --- Yes, I ___________ there three times.
Why not ______ your teacher for advice when you don’t know ______ the problems?
--- Didn’t your brother ________ go to school by bike? --- Yes, he did. But he ________ walking to school now.