—Sorry, I forgot to call Jack to tell him about our plan tomorrow.—Never mind. You ____________ anyway. I called him yesterday.
To those scientists, it still remains to be a question ______ man can go back to the old days with time machine.
There is a common belief among them _______ rubbish can and should be put into good use.
We never doubt ______ our school team will win the match against No. 3 Middle School.
The teacher usually grades the students on _______ they have behaved.
Once _____, it won’t be easily forgotten.