We can never expect____ bluer sky unless we create_____less polluted world.()
He was ready to take the________ of being drowned himself to save the drowning child.
Once you have become _______ to cigarette smoking or alcohol, it is hard to _______it even though you try hard.
I found it very difficult to get ________up so early before, but I did finally_________.
The old man said the accident________ careless driving
I don’t think _________ is possible to master a foreign language without much memory work.