Thousands of years ago, people killed the wild horse that lived around _____ food. _____ time, people began to catch and raise animals .
It's no secret to us, but he alone is in the dark. It means ____.
Every year, ____ graduates take pan in TOEFL for further education abroad.
In order to ____ the debt, the couple has worked hard for years with little food and only a small room to live in and never a moment's rest.
---What do you think of my suggestion? --- Sorry. What's that? I ____ about something else.
Never did we have to play "stand up", "sit down", "speak out". I don't ____ one student who didn’t try his best.