七、完成句子

Your mother asked me to tell you that you didn't have to (needn't, don't have to, won't have to, there is (was)no need for you to, don't need to, wouldn't have to)worry about her health.
It took him more than(over)three hours to translate the article from English into Chinese.
It is well known that more than(over)seventy percent(70%)of the surface of the earth is covered with(by)water. (⋯water covers more than seventy percent of the surface of the earth.
Ways must be found to prevent(stop)the factory from pouring(draining, sending)waste water into the river.
If the wounded driver had been treated without delay, he could (would, might)have been saved.
What I see in the city today is completely(entirely)different from(completely differs from)what (that which)I saw when I lived (was,was living)here thirty years ago.
My opinion is that the question you(have)just asked (you asked just now)has nothing to do with(has no relation to)our plan.