The roof fell ____ he had time to rush out.
He couldn't __________ his father that John was telling the truth.
Nobody could understand her though she tried to __________ her idea by using the simplest English, because they are foreigners.
We don't know that plan __________ by the teacher is __________ three parts.
Once new difficulties __________ in your work, it's always important to use your brains.
-What is the price of petrol these days?-Oh, it __________ sharply since last month.