Bill and his sister Sally enjoyed ________ at the dancing party.

The environment is becoming worse and worse. I think we should do something to ____ people ____ cutting the trees in order to protect the earth.

I need lots of money to —— for my education.

Qingdao is a good place for summer vacation. My father ___________ there several times.

I once heard him ____ that a rainbow was a bridge from earth to heaven.