This time I included only the sentences I wasn' sure of.

1)When describing one's family, are all these alternatives possible?
My family consists of/ is made up of/is composed of/is formed by three people: my father, my mother and I (or me?). In my family there are three people.
2) I'm in charge of feeding my dog.
3) In August I went to the annual village festival. A cattle fair was held for the occasion where farmers took their animals.
4) I helped waiting at table.
5) I went to a holiday club in Sicily.
The hotel club's entertainers staged a different performance every evening. We were invited to take part in it, too.I regretted coming back home.
6) I attend (or go to) a high school with an emphasis on science (or scientific lyceum??). I'm in the second year now. /I'm attending the second class at the moment.
7)I chose this course of study because I'm more interested in scientific subjects than in humanities (OR arts Or liberal studies??)
Thank you.

1. and I.

4. or waiting on tables

Any of the other possibilities are good.

sra

1) When describing one's family, all of the alternatives you mentioned are possible. You can say "My family consists of," "My family is made up of," "My family is composed of," or "My family is formed by" three people: my father, my mother, and I" or "my father, my mother, and me." Another alternative is to say "In my family, there are three people."

2) "I'm in charge of feeding my dog" is a grammatically correct sentence. It means that it is your responsibility to give food to your dog.

3) "In August, I went to the annual village festival. A cattle fair was held for the occasion where farmers took their animals." This sentence describes your visit to the festival and mentions that there was a specific cattle fair where farmers brought their animals.

4) "I helped waiting at table." This sentence is not grammatically correct. It should be "I helped with waiting tables" or "I helped serve at the table." These phrases mean that you assisted in serving food and taking care of customers at a restaurant or event.

5) "I went to a holiday club in Sicily. The hotel club's entertainers staged a different performance every evening. We were invited to take part in it, too. I regretted coming back home." This paragraph describes your experience at a holiday club in Sicily. It mentions that the hotel club's entertainers performed different shows every evening, and you were invited to participate. The last sentence suggests that you felt a sense of regret upon returning home from this enjoyable experience.

6) "I attend (or go to) a high school with an emphasis on science (or scientific lyceum??). I'm in the second year now" or "I'm attending the second class at the moment." These sentences provide information about your current education situation. They mention that you are enrolled in a high school that focuses on science or a scientific lyceum. Additionally, you state that you are currently in the second year or attending the second class.

7) "I chose this course of study because I'm more interested in scientific subjects than in humanities (OR arts OR liberal studies??)." This sentence explains your reason for selecting a particular course of study. It states that your preference for scientific subjects motivated your choice, as opposed to humanities, arts, or liberal studies.