. ______we’ll be able to drive a car______ by electricity, solar energy in about ten years.

Mike was usually so careful, ______this time he made a small mistake.

He was beaten by his father because of being naughty. ____, he became silent.

We haven’t heard from her for long, so we give her_____for dead.

-- Do you think it's a good idea to make friends with your students?--  _____  , I do. I think it's a great idea.