Because there is not a linguistic census in France, as there is for Britain, there is difficulty in estimating the number of speakers of Breton, a Celtic language.
Because there is not a linguistic census in France, as there is for Britain, there is difficulty in estimating
Because there is no linguistic census in France, unlike Britain, it is difficult to estimate
Unlike Britain, there is no linguistic census in France, and that fact makes for difficulty in estimating
There is not a linguistic census in France, as there is for Britain, a fact making for difficulty in the estimation of
There is no linguistic census in France, as there is in Britain, a fact that makes it difficult to estimate
The sentence suggests that because France, unlike Britain, has no linguistic census, it is difficult to estimate how many people in France speak Breton.
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