---–I was riding along the street and all of a sudden, a car cut in and knocked me down.. -----You can never be ________ careful in the street.
It will be many years ______the doctors and medical scientists can find _____ for cancer.
We have to ______ everything question in detail ______ we take action.
It is clear that no use can be made ______radium _____we don’t know clearly the characteristics of it.
From my point of view, the theory that ______ by the scientist is not quite scientific.
The invention of steam engine greatly sped up the industrial revolution, which _____ a lot to the take-off of the world.