John is very lazy. He falls ______ behind in his studies.
With nothing __________ to burn, the fire became weak and finally died out.
He is very popular among his students as he always tries to make them __________ in his lectures.
All the members were __________ the proposal.
Professor Jordon is well known for his __________ into the habits of the common housefly.
It has been raining every day so far. I hope tomorrow will __________ fine.