Within a few years China ____ well have the most advanced railway industry in the world.

--- I can’t find my purse anywhere . --- You ___ have lost it while shopping .

I’m fond of my sister, but she has a serious shortcoming. She _______ be really stubborn.

We _______ talk loudly when we see the sign “ Be quiet ”on the right. 

Don't blame such a small boy any more. Even the wisest___ make a mistake sometimes.