It is pretty well understood_______ controls the flow of carbon dioxide in and out the atmosphere today.
What led you _______ that Bob might be the thief ?.
I think, the Chinese teacher will surely give _____ on your composition.
Rather than ________ the crowded bus, I prefer _________ to school.
After the new technique was introduced, the factory produced _______ cars in 2009 as 10 year before.
— What do you think made Mary so upset?— __________ her new bicycle.