I just need to know if the sentences are correct though they are not complete. Thank you.

1) Imagine a school in which both German, French, English are studied...
The school has got 130 students,45 of whom study only English whereas ..... study both English and French.
None of (among) them studies both English and German.

The word "both" is used only with two people or things. Remove it, and add "and" after "French," in #1.

space after comma

comma after "English" in 2nd sentence

delete "(among)"

To determine if the sentences are correct, we can analyze them one by one.

1) "Imagine a school in which both German, French, English are studied..."
This sentence is grammatically correct. It describes a hypothetical situation where a school offers the study of German, French, and English languages.

2) "The school has got 130 students, 45 of whom study only English whereas..... study both English and French."
This sentence is not complete, as there is missing information after the word "whereas." To further complete the sentence, you should add the specific number of students who study both English and French.

An example of a complete sentence could be: "The school has 130 students, 45 of whom study only English whereas 25 students study both English and French." Here, we have clearly stated the number of students who study both English and French.

3) "None of (among) them studies both English and German."
This sentence is grammatically correct, but it lacks context. Without additional information, it is unclear whom "them" refers to. To make it clear, you should specify the group of people you are referring to. For example, you could say: "Among the students, none of them studies both English and German."

In summary, while the first sentence is grammatically correct, the second and third sentences require additional information to be complete and clear.