Our football team led ______ one point, but towards the end of the game, their team scored and the game ended ______ a tie.

Carbon dioxide ___ from burning fuels is the most common of the so-called greenhouse gases.

I will appreciate ______ if you can give me a hand.

Was it in the school reading room _____ you found the missing book?

Young men should constantly _________their own state of mind so as to adapt to the circumstances in which fierce competition is going on .