—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. 

My car ______ down just when I need it most. I have to get it repaired. 

When he was alive, the old scientist used to say that knowledge ______ from practice and he gained his experience by doing a lot of practical work.

---Where have you been recently? --- I _______ in Hangzhou on business for a week last month.

The country life he was accustomed to________ greatly since 1992.