Well, I understand. But, I came up with that in order to be able make faster contributions. I am having to spend a lot of time trying to find the sentence that is not translated into my target languages. It might be that others are facing the same problem. It would be a part of the aim of the project for people to make more contributions.

Yes, but you can't choose random combinations. For example someone who wants only sentences that are translated to say German, French and Spanish at the same time, it would be very useful to allow any number of selected translations. Another thing is, when a t
contributor wants only those sentences that are not translated to his target language (so as to be faster) he cannot choose the languages to exclude. One of us could be, say, looking for sentences which have both Japanese and Russian translations and lacking Turkish and English translations, it would be nice to offer that flexibility...

2 IMPORTANT SUGGESTIONS to the HOST:
For translators, it would be great to be able to select which language or which combination of languages to be excluded, so that he can find only the sentences that haven't been translated to his target language.
For readers:
It would be very useful for them to be able to look up only the sentences that combine, at once, translations of those languages they want to see together.