As time__________, she became more and more anxious about  her son’s safety. 

---We all had a lot of fun at the barbecue yesterday. Pity you weren’t there. ---I really should have gone with you, but I ________ on some remaining problems. 

After 15 years in the USA, he has finally decided to _____ American citizen-ship.

Despite ongoing street protests, US beef ________ in South Korea due to its lower price.

 — Why are you always yawning, Kathy? —I ______ all night reading Steve Jobs. That’s a fantastic book!