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Belhda
Hello, I'd like to know if the following sentence is correct. "Children breathing rate is twice as much as adults'."
I think it should be *Children breathing rate is twice more than adults.*
You have a breathing rate of something. That is a posessive. On top of that, the something is plural. Therefore you need the plural possessive. http://www.meredith.edu/grammar/plural.htm
Thank you for your answer, but I still can't get it. What I mean is that breathing rate of children is the double of the rate of adults breathing rate. Would it be right :to say, " children's breathing rate is twice as much as adults' " ?
Yes. "Children's breathing rate is twice as much as adults'." "A child's breathing rate is twice as much as an adult's." "Children's breathing rate is twice that of adults'." And so on.