The two boys fought and fought until one ______.
I hate ___ when the weather in Changsha becomes freezing cold because there is no heater inside.
. --- Believe it or not, I passed the driving test at the first attempt yesterday.--- Great! But remember you can never be ___ careful when driving a car in the street.
--- Tom is so joyful that he smiles at everyone. --- So ___ you if you get the first in the exam.
--- Who do you think ___ the book here? --- It may be John. He was sitting here all the morning.
David can speak idiomatic American English and yet, _____ English, he doesn't know it at all.