Who does homework , Tom, Jack or Bill—Bill.

The scientists are now trying to discover that use could be _________ such material.

On his way back home, he an interesting story on the bus.

Could you please tell Lucy that I want to talk to her —Sure, I will tell her as soon as she _______ back.

With the word “PM2.5” ____ appearing in media reports, people pay greater attention to it and seek health tips for smoggy days.