I am pupil/ she is a clever girl/ you are a good girl
social networking websites, social networking sites, social network - более официальные термины.
В неофициальных источниках я встречала просто "nets", но его лучше не использовать без крайней нужды)
SoNet site также популярно, оно есть в оф.словаре
Hello Lukas ! My name is .... . I'm from Russia . I love tasty food very much ! I can tell you about my favorite food !
I love ice cream ! Ice cream very tasty , my brother eat him every day !
And I love spaghetti . It's my favorite food ! I love spaghetti with tomatoes and cheese .
Dear Lukas , thank you for your letter
Her new book sells like hot cakes.
I saw a lot of celebrities,but meeting Beyoncé was the icing on the cake.
English homework was a piece of cake for me.
She has to make up her mind what is more important: to hang out with friends now or to continue her education.She can't have her cake and eat it