Alright class, let's complete the exercise by choosing between "all" and "both" for each sentence.
1. - What films do you like? - I like **all** French films.
* Explanation: Since the question is about what films in general the person likes, "all" is more appropriate.
2. - Where are your sisters? – They are **both** on a trip to Moscow.
* Explanation: Since the person has sisters (plural) and they are together on a trip, "both" makes sense.
3. - Where do you stay in St. Petersburg? - I can **both** go to my friends and stay in a hotel.
* Explanation: I can do both things: go to my friends and stay in a hotel
4. - Are you the youngest in the team? – No, **all** of my teammates are younger than me.
* Explanation: Since the person wants to explain that every teammate is younger than him, "all" is more suitable.
5. - You gave me two answers. Which one is correct? - **Both** are correct.
* Explanation: Since there are two answers in question, the correct option is "both".